N.J. Ct. R. 4:26-3

(a) Representation by Presumptive Taker. In an action affecting property in which any person in being or unborn has or may have a future interest other than a life or lesser estate, or where it is not known or is difficult to ascertain who is the person or class having such interest, it shall be necessary to join as parties to the action only the person or persons who would be entitled to such property if the event or contingency terminating all present estates and successive life or lesser estates therein had occurred on the date of the commencement of the action, and the judgment entered therein shall be binding upon all persons, whether in being or not, who may claim the future interest in the property, unless it shall affirmatively appear in the action that there exists a conflict of interest between the persons so joined and the persons not joined. Should such conflict exist, the court may, in its discretion, appoint from among the persons then next entitled upon the occurrence of the event or contingency, one person to represent all persons (whether in being or not) who may claim any future interest in the property.

(b) Representation by Donee of Power of Appointment. Where a party to an action is the donee of a power of appointment of any type, it shall not be necessary to join the potential or permissible appointees of the power or takers in default, and the judgment entered therein shall be binding upon the appointees, unless it shall affirmatively appear in the action that there exists a conflict of interest between the donee of the power and the appointees.

(c) Representation by Other Parties or Guardians. In an action in which the interests of a person not in being are or may be affected or in which it is not known or is difficult to ascertain who is the person or class affected thereby and as to which paragraphs (a) and (b) are inapplicable because of the lack of a representative as therein described or because of the nature of the interest involved, the court, in its discretion, may appoint a party to the action to represent such persons, and the judgment entered therein shall be binding upon the persons so represented. If, however, it shall appear that no party to the action adequately represents the interests of such persons, the court shall appoint a guardian ad litem to represent them.

(d) Joinder of Additional Parties. Notwithstanding paragraphs (a), (b) and (c) hereof, the court, in its discretion, may require the joinder of additional persons.