1. (1) All persons may be joined in one action as plaintiffs in whom any right to relief in respect of or arising out of the same transaction or series of transactions is alleged to exist, whether jointly, severally, or in the alternative, where, if such persons brought separate actions, any common question of law or fact would arise; provided that if, upon the application of any defendant, it shall appear that such joinder may embarrass or delay the trial of the proceeding, the Court may order separate trials or make such order as may be expedient.
(2) In a case under this rule judgment may be given for such one or more of the plaintiffs as may be found to be entitled to relief, for such relief as he or they may be entitled to, without any amendment but the defendant, though unsuccessful, shall be entitled to his costs occasioned by so joining any person who shall not be found entitled to relief, unless the Court shall otherwise direct.
2. Where an action has been commenced in the name of the wrong person as plaintiff, or where it is doubtful whether it has been commenced in the name of the right plaintiff, the Court may, if satisfied that it has been so commenced through a bona fide mistake, and that it is necessary for the determination of the real matter in dispute so to do, order any other person to be substituted or added as plaintiff upon such terms as may be just.
3. Where in an action any person has been improperly or unnecessarily joined as a co-plaintiff, and a defendant has set up a counter-claim or set-off, he may obtain the benefit thereof by establishing his counterclaim or set-off as against the parties other than the co-plaintiff so joined, notwithstanding the misjoinder of such plaintiff or any proceeding consequent thereon.
4. All persons may be joined as defendants against whom the right to any relief is alleged to exist, whether jointly, severally, or in the alternative. Judgment may be given against such one or more of such defendants as may be found to be liable, according to their respective liabilities, without any amendment.
5. It shall not be necessary that every defendant shall be interested as to all the relief prayed for, or as to every cause of action included in any proceeding against him; but the Court may make such order as may appear just to prevent any defendant from being embarrassed or put to expense by being required to attend any proceedings in which he may have no interest.
6. The plaintiff may, at his option, join as parties to the same action all or any of the persons severally, or jointly and severally, liable on any one contract, including parties to bills of exchange and promissory notes.
7. Where the plaintiff is in doubt as to the person from whom he is entitled to redress he may join two or more defendants, to the intent that the question as to which, if any, of the defendants is liable, and to what extent, may be determined as between all parties.
8. Trustees, executors, and administrators may sue and be sued on behalf of or as representing the property or estate of which they are trustees or representatives, without joining any of the persons beneficially interested in the trust or estate, and shall be considered as representing such persons; but the Court may, at any stage of the proceedings, order any of such persons to be made parties either in addition to or in lieu of the previously existing parties. This rule shall apply to trustees, executors and administrators sued in proceedings to enforce a security by sale or otherwise.
9. Where there are numerous persons having the same interest in one cause or matter, one or more of such persons may sue or be sued, or may be authorised by the Court to defend, in such cause or matter, on behalf, or for the benefit, of all persons so interested.
10. Where in proceedings concerning a trust a compromise is proposed, and some of the persons interested in the compromise are not parties to the proceedings, but there are other persons in the same interest before the Court and assenting to the compromise, the Court, if satisfied that the compromise will be for the benefit of the absent person and that to require service on such persons would cause unreasonable expense or delay, may approve the compromise and order that the same shall be binding on the absent persons, and they shall be bound accordingly, except where the order has been obtained by fraud or non-disclosure of material facts.
11. Any person proceeding to prove a will in solemn form, or to revoke the probate of a will, may, if the will affects real estate, apply to the Court for an order authorising him to cite or make the heir or heirs-at-law, or other person or persons having or pretending interest in such real estate, a party or parties to the action, and the Court, on being satisfied by affidavit that the will in question does affect or purport to affect the real estate, may make an order authorising the person applying to cite the heir or heirs-at-law or such person or persons as aforesaid; provided always that the Court may give any special directions which it may think the justice of the case requires.
12. Subject to the provisions of the Acts and these Rules, in all probate actions the rules as to parties and as to citations to see proceedings in use in the Court of Probate immediately before 1st January, 1878, shall continue to be in force. Citations to see proceedings shall issue from the Central Office.
13. No cause or matter shall be defeated by reason of the misjoinder or non-joinder of parties, and the Court may in every cause or matter deal with the matter in controversy so far as regards the rights and interests of the parties actually before it. The Court may at any stage of the proceedings, either upon or without the application of either party, and on such terms as may appear to the Court to be just, order that the names of any parties improperly joined, whether as plaintiffs or as defendants, be struck out and that the names of any parties, whether plaintiffs or defendants, who ought to have been joined, or whose presence before the Court may be necessary in order to enable the Court effectually and completely to adjudicate upon and settle all the questions involved in the cause or matter, be added. No person shall be added as a plaintiff suing without a next friend, or as the next friend of a plaintiff under any disability, without his own consent in writing thereto. Every party whose name is so added as defendant shall be served with a summons or notice in manner hereinafter mentioned, or in such other manner as the Court may direct, and the proceeding as against such party shall be deemed to have begun only on the making of the order adding such party.
14. Any application to add or strike out or substitute a plaintiff or defendant may be made to the Court at any time before trial by motion or at the trial of the action in a summary manner.
15. Where a defendant is added or substituted the plaintiff shall, unless otherwise ordered by the Court, file an amended copy of and take out a summons and serve such new defendant with such summons or notice in lieu thereof in the same manner as original defendants are served. If a statement of claim has been delivered previously to such defendant being added, the same shall, unless otherwise ordered by the Court, be amended in such manner as the addition or substitution of such new defendant shall render necessary or desirable, and a copy of such amended statement of claim shall be delivered to such new defendant at the time when he is served with the summons or notice or afterwards within four days after his appearance.
16. An infant may sue as plaintiff by his next friend in the manner heretofore in use, and may, in like manner, defend by his guardian appointed for that purpose. On the infant's attaining full age, the next friend or guardian may apply to the proper officer in the Central Office, by production of the infant’s birth certificate or such other evidence as the proper officer may require, for an amendment of the title to the proceedings to describe the party lately an infant as proceeding or defending in his own name. The said officer shall on such application cause the title to the proceedings in the cause book to be amended accordingly.
17. A person of unsound mind may sue as plaintiff by his committee or next friend, and may defend by his committee or guardian appointed for that purpose.
18. An infant shall not enter an appearance except by his guardian ad litem. No order for the appointment of such guardian shall be necessary, but the solicitor applying to enter such appearance shall make and file an affidavit in the Form No 4 in Appendix A, Part II.
19. Every infant served with a petition or notice of motion or other document in a matter, shall appear on the hearing thereof by a guardian ad litem, in all cases in which the appointment of a special guardian is not provided for. No order for the appointment of such guardian shall be necessary, but the solicitor by whom he appears shall previously make and file an affidavit as in rule 18 mentioned.
20. Before the name of any person shall be used in any cause or matter as next friend of any infant or other party, or as relator, such person shall sign a written authority to the solicitor for that purpose, and the authority shall be filed in the proper office.
21. In all causes or matters to which any infant or person of unsound mind, whether so found by inquisition or not, or person under any other disability, is a party, any consent as to the mode of taking evidence or as to any other procedure shall, if given with the consent of the Court by the next friend, guardian, committee or other person acting on behalf of the person under disability, have the same force and effect as if such party were under no disability and had given such consent. Provided that no such consent by the committee of any person of unsound mind shall be valid as between him and such person, unless given with the sanction of the President of the High Court.
III. Administration and execution of trusts
22. (1) In any case in which the right of an heir-at-law, or the next-of-kin, or a class, shall depend upon the construction which the Court may put upon an instrument and it shall not be known or shall be difficult to ascertain who is or are such heir-at-law or next-of-kin or class, and the Court shall consider that in order to save expense or for some other reason it will be convenient to have the questions of construction determined before such heir-at-law, next-of-kin or class shall have been ascertained by means of inquiry or otherwise, the Court may appoint some one or more persons to represent such heir-at-law, next-of-kin or class, and the judgment of the Court in the presence of such persons shall be binding upon the heir-at-law, next-of-kin or class so represented.
(2) In any other case in which an heir-at-law, or any next-of-kin, or a class shall be interested in any proceedings, the Court may, if, having regard to the nature and extent of the interest of such persons or any of them, it shall appear expedient on account of the difficulty of ascertaining such persons, or in order to save expense, appoint one or more persons to represent such heir, or to represent all or any of such next-of-kin or class, and the judgment or order of the Court in the presence of the persons so appointed shall be binding upon the persons so represented.
23. Any residuary legatee or next-of-kin entitled to a judgment or order for the administration of the personal estate of a deceased person may have the same without serving the remaining residuary legatees or next-of-kin.
24. Any legatee interested in a legacy charged upon real estate, and any person interested in the proceeds of real estate directed to be sold, and who may be entitled to a judgment or order for the administration of the estate of a deceased person, may have the same without serving any other legatee or person interested in the proceeds of the estate.
25. Any residuary devisee or heir entitled to the like judgment or order may have the same without serving any co-residuary devisee or co-heir.
26. Any one of several cestuis que trustent under any deed or instrument entitled to a judgment or order for the execution of the trusts of the deed or instrument may have the same without serving any other cestui que trust.
27. In all cases of actions for the prevention of waste or otherwise for the protection of property, one person may sue on behalf of himself and all persons having the same interest.
28. Any executor, administrator, or trustee entitled thereto may have a judgment or order against any one legatee, next-of-kin or, cestui que trust for the administration of the estate or the execution of the trusts.
29. Any mortgagee or other incumbrancer on land entitled to a sale of the mortgaged lands may have a judgment or order for such sale without serving any other mortgagee or incumbrancer, or a trustee for such mortgagee or incumbrancer, unless such mortgagee, incumbrancer, or trustee is in the actual possession or receipt of the rents and profits of the mortgaged or incumbered lands; provided always, that a person, at whose suit or for whose benefit a receiver or sequestrator has been appointed or extended, or continues to receive the rents and profits of the lands, shall not be deemed to be in receipt of such rents and profits within the meaning of this rule.
30. The Court may require any person to be made a party to any action or proceeding, and may give the conduct of the action or proceeding to such person as the Court may think fit, and may make such order in any particular case as it may think just for placing the defendant on the record on the same footing in regard to costs as other parties having a common interest with him in the matters in question.
(a) any order has been made under section 31 of the Land and Conveyancing Law Reform Act 2009, or
(b) in any action for the administration of the estate of a deceased person, or the execution of the trusts of any deed or instrument, or for the partition or sale of any hereditaments, a judgment or order has been pronounced or made:
(i) for an account; or
(ii) under Order 33; or
(iii) affecting the rights or interests of persons not parties to the action; the Court may direct that any person affected by the order under section 31 of the said Act or interested in the estate or under the trust or in the hereditaments shall be served with notice of the judgment or order; and after such notice such persons shall be bound by the proceedings in the same manner as if they had originally been made parties and shall be at liberty to attend the proceedings under the judgment or order. Any person so served may, within one month after such service, apply to the Court to discharge, vary or add to the judgment or order.
32. It shall not be necessary for any person served with notice of any judgment or order to obtain an order for liberty to attend the proceedings under such judgment or order, but such persons shall be at liberty to attend the proceedings upon entering an appearance in the same manner and subject to the same provisions as a defendant entering an appearance.
33. Notice of a judgment or order served pursuant to rule 31 shall be entitled in the action and there shall be indorsed thereon a memorandum in the Form No 30 in Appendix G.
34. A memorandum of the service upon any person of notice of the judgment or order in any action under rule 31 shall be filed in the Central Office upon due proof by affidavit of such service. The memorandum shall be in the Form No 31 in Appendix G.
35. Notice of a judgment or order served pursuant to rule 31 on an infant or person of unsound mind not so found by inquisition shall be served in the same manner as an originating summons in an action. At any time during the proceedings under any such order, the Court may require a guardian ad litem to be appointed for any infant or person of unsound mind not so found by inquisition, who has been served with notice of such order.
36. In any cause or matter to execute the trusts of a will it shall not be necessary to make the heir-at-law a party, but the plaintiff shall be at liberty to make the heir-at-law a party where he desires to have the will established against him.
37. If in any cause, matter, or other proceeding it shall appear to the Court that any deceased person who was interested in the matter in question has no legal personal representative, the Court may proceed in the absence of any person representing the estate of the deceased person or may appoint some person to represent his estate for all the purposes of the cause, matter or other proceeding on such notice to such persons, if any, as the Court shall think fit, either specially or generally by public advertisement, and the order so made, and any order consequent thereon, shall bind the estate of the deceased person in the same manner in every respect as if a duly constituted legal personal representative of the deceased person had been a party to the cause, matter or proceeding.
38. In any cause or matter for the administration of the estate of a deceased person no party other than the executor or administrator shall, unless by leave of the Court, be entitled to appear at any stage on the claim of any person not a party to the cause or matter against the estate of the deceased person in respect of any debt or liability. The Court may direct or give liberty to any other party to the cause or matter to appear, either in addition to or in the place of the executor or administrator, upon such terms as to costs or otherwise as the Court may think fit.
39.  (1) “company” means, as the case may be, either—
(a) an “existing company”, within the meaning of section 2(1) of the Companies Act 2014, or
(b) a company capable of being wound up under the Companies Act 2014.
(2) Subject to the provisions of this rule, a derivative action may not be commenced without the leave of the Court, given in accordance with this rule.
(3) An application for leave to commence a derivative action shall be made by Originating Notice of Motion in which is sought:
(a) the leave of the Court to commence the derivative action;
(b) where relevant, an order requiring the company to indemnify the applicant in respect of the whole or part of the costs and expenses reasonably incurred by the applicant in conducting the derivative action (including any costs for which the applicant may be made liable in such action), and
(c) any interim relief of an urgent nature.
(4) The Originating Notice of Motion shall be entitled “In the matter of an intended derivative action” on the application of the applicant. The company shall be named as a respondent.
(5) The Originating Notice of Motion shall be supported by an affidavit:
(i) setting out the nature and extent of the evidence available to support the applicant’s claim to be a person entitled to bring the intended derivative action;
(ii) setting out the nature and extent of the evidence available to support the applicant’s assertion that the company is entitled to make the claim to which the intended derivative action relates, and where such evidence is of an expert or technical nature, the substance of that evidence shall be provided to the Court in a report of a qualified person verified by its author and exhibited to the grounding affidavit, or in other suitable form;
(iii) setting out the basis of the deponent’s belief as to the existence of the facts or circumstances referred to in paragraphs (i) and (ii);
(iv) specifying the efforts, if any, made by the applicant to cause the company to prosecute the claim concerned;
(v) setting out the basis on which it is alleged that it is reasonable and prudent in the interests of the company that the applicant be given leave to commence the intended derivative action;
(vi) including evidence, where available, of the views of members other than the applicant;
(vii) to which is exhibited an opinion of counsel as to whether the applicant has a realistic prospect of success in the intended derivative action; and
(viii) to which is exhibited a draft of the summons or other originating document, and a draft of any statement of claim, in the intended derivative action.
(6) Unless the Court otherwise directs, a respondent shall be served with copies of the Originating Notice of Motion, of the grounding affidavit and any exhibits thereto at least 21 days before the date first fixed for the hearing of the Originating Notice of Motion.
(7) Where the Court is satisfied on the ex parte application of the applicant that service of the Originating Notice of Motion would be likely to frustrate some party of a relief sought, the Court may hear and determine ex parte an application for some relief sought in the Originating Notice of Motion.
(8) A respondent who has been served with the Originating Notice of Motion and who intends to oppose the application may file in the Central Office a replying affidavit setting out his grounds of opposition and verifying any facts or circumstances relied on, and shall serve a copy of any such affidavit and any exhibits thereto on the applicant and on any other respondent not later than seven days before the return date of the Originating Notice of Motion.
(9) The applicant shall be at liberty to file a further affidavit replying to any matter verified in an affidavit of a respondent, in which event a copy of that affidavit shall be served upon the respondent before the return date of the Originating Notice of Motion.
(10) An affidavit giving the names and addresses of, and the places and dates of service on, all persons who have been served with the Originating Notice of Motion, grounding affidavit and exhibits (if any) shall be filed by the applicant before the motion is heard.
(11) On the return date of the Originating Notice of Motion (or on any adjournment from such date), the Court may, in addition to any other order it may make:
(a) direct service of notice of the application on any other member or other person, including mode of service and the time allowed for such service (and the Court may for that purpose adjourn the hearing or further hearing of the application to a date specified);
(b) give directions as to the filing and delivery of any further affidavits;
(c) make such orders and give such directions (including a direction that a meeting of members take place) as it considers appropriate for the purpose of ascertaining the views of members whose interest in the subject matter of the proposed derivative action is independent of that of the applicant and the respondent;
(d) where the court has directed in accordance with the preceding paragraph that a meeting of members shall take place, give directions as to the convening and conduct of the meeting and for the reporting to the Court of the proceedings at the meeting;
(e) give a direction that the application be determined by way of plenary hearing, where it appears to the Court that the subject matter of the application is likely to involve a substantial dispute of fact or it is otherwise necessary or desirable in the interests of justice (and the Court may for that purpose make orders and give directions in relation to the exchange of pleadings or points of claim or defence between the parties);
(f) give directions as to the furnishing by the parties to the Court and delivery of written submissions;
(g) give directions as to the publication of notice of the hearing of the application and the giving of notice in advance of such hearing to any person other than a party to the proceedings who desires to be heard on the hearing of the application;
(h) hear and determine any application for relief of an interlocutory nature, whether in the nature of an injunction or otherwise.
(12) Save where the Court otherwise directs, any evidence in proceedings to which this rule relates shall be given on affidavit.
(13) An order made on an application under sub-rule (3) may:
(a) give leave to commence a derivative action on such terms or conditions as the Court sees fit to impose;
(b) give leave to continue a derivative action only until the close of pleadings, the completion of discovery, or some other specified step in the proceedings or until a specified date, and require a further application for leave to continue the derivative action beyond that step or date;
(c) require the company for the benefit of which a derivative action is allowed to be brought to indemnify the applicant in respect of the whole or part of costs and expenses reasonably incurred by the applicant in conducting the derivative action (including any costs for which the applicant may be made liable in such action);
(d) order that the derivative action may not be discontinued or compromised without the leave of the Court;
(e) give such directions and include such orders for the conduct of the proceedings on the derivative action as appear convenient for the determination of those proceedings in a manner which is just, expeditious and likely to minimise the costs of those proceedings.
(14) Where a claim which might be the subject of a derivative action arises in proceedings pending before the Court, the provisions of this rule shall, with the necessary modifications, apply to such a claim, provided that the application referred to in sub-rule (2) may, in lieu of being brought by Originating Notice of Motion, be made by motion on notice in the pending proceedings, and the Court may make any order it considers just:
(a) dispensing with any requirement of this rule, where it considers it appropriate to do so having regard to the proceedings had in the pending proceedings; or
(b) as to the hearing of the application.
(15) An application for an order that the applicant be given conduct of proceedings and continue those proceedings as a derivative action shall be made by motion on notice in the proceedings concerned. The motion shall be grounded on an affidavit sworn by or on behalf of the moving party which shall:
(a) set out the grounds on which the applicant claims that the proceedings should continue as a derivative action, and verify any facts and circumstances relied on in that regard; and
(b) set out the nature and extent of the evidence available to support the applicant’s claim to be a proper person to continue the proceedings as a derivative action.
(16) An application for an order substituting another person to have conduct of a derivative action shall be made by motion on notice in the proceedings on the derivative action. The motion shall be grounded on an affidavit sworn by or on behalf of the moving party which shall:
(a) set out the grounds on which the moving party claims such substitution is necessary or desirable, and verify any facts and circumstances relied on in that regard; and
(b) set out the nature and extent of the evidence available to support the claim that the person proposed to be substituted is a proper person to continue the proceedings as a derivative action.
(17) A member referred to in sub-rule (1) may apply for leave to defend on behalf of a company a claim or a counter-claim against such company, and the provisions of this rule other than this sub-rule shall, with the necessary modifications, apply to such an application.
(18) Where, in accordance with law, an action may be authorised by leave of the Court:
(a) in which a claim is made on behalf of a body corporate (which is not a company) by a member of that body; or
(b) in which a claim is made on behalf of an unincorporated association or body by a member of that association or body,
the provisions of this rule shall, unless the Court otherwise directs or permits, apply mutatis mutandis to any application for leave to commence or to have conduct of such an action, to the proceedings on any such application and to the conduct of any such action for which leave is given as if the references in this rule to a “company” (and to its members) included references to the body corporate or unincorporated association or body concerned (and to its members).
 Order 15 rule 16 substituted by SI 83 of 2016, effective 25 February 2016.
 Order 15 rule 31 substituted by SI 149 of 2010, effective 10 May 2010. SI 149 of 2010 is effective 10 May 2010, subject to paragraph 2 which reads: “Any application for registration of a lis pendens containing the particulars required by law before 1 December 2009 for such registration which is received after 1 December 2009 and prior to the date mentioned in paragraph 1 shall be deemed to comply with the requirements for registration of a lis pendens in accordance with section 121 of the Land and Conveyancing Law Reform Act 2009.”
 Order 15 rule 39 inserted by SI 503 of 2010, effective 16 November 2010.
 Order 15 rule 39(1) substituted by SI 255 of 2015, effective 1 July 2015.