Commonwealth Consolidated Regulations Commonwealth Consolidated RegulationsTwo or more persons may be joined as plaintiffs or as defendants in any proceeding:
(a) where the Court or a Justice, before or after the joinder, gives leave to do so; or
(b) where
(i) if separate proceedings were brought by or against each of them, some common question of law or fact would arise in all of the proceedings; or
(ii) all rights to relief in the proceeding (whether joint, several or alternative) are in respect of or arise out of the same transaction or series of transactions.