Rules on Civil Procedure
Section 1. Who may intervene. - A person who has a legal interest in the matter in litigation, or in the success of either of the parties, or an interest against both, or is so situated as to be adversely affected by a distribution or other disposition of property in the custody of the court or of an officer thereof may, with leave of court, be allowed to intervene in the action. The court shall consider whether or not the intervention will unduly delay or prejudice the adjudication of the rights of the original parties, and whether or not the intervenor's rights may be fully protected in a separate proceeding. (2[a], [b]a, R12)