Mass. Gen. Laws ch. 228, § 7: Death of joint plaintiff or defendant

Section 7. If any of several plaintiffs or defendants in a personal action, the cause of which survives, dies before final judgment, the action may be prosecuted by the surviving plaintiff or against the surviving defendant, as the case may be. If all the plaintiffs or defendants die, the action may be prosecuted or defended by or against the executor or administrator of the last surviving plaintiff or defendant, respectively.