Rules on Civil Procedure
Section 6. Permissive joinder of parties. - All persons in whom or against whom any right to relief in respect to or arising out of the same transaction or series of transactions is alleged to exist, whether jointly, severally, or in the alternative, may, except as otherwise provided in these Rules, join as plaintiffs or be joined as defendants in one complaint, where any question of law or fact common to all such plaintiffs or to all such defendants may arise in the action; but the court may make such orders as may be just to prevent any plaintiff or defendant from being embarrassed or put to expense in connection with any proceedings in which he may have no interest. (6n)