[Appointment or Testacy Proceedings; Conflicting Claim of Domicile in Another State.]\nIf conflicting claims as to the domicile of a decedent are made in a formal testacy or appointment proceeding commenced in the commonwealth, and in a testacy or appointment proceeding after notice pending at the same time in another state, the court of the commonwealth shall stay, dismiss, or permit suitable amendment in, the proceeding here unless it is determined that the local proceeding was commenced before the proceeding elsewhere. The determination of domicile in the proceeding first commenced shall be accepted as determinative in the proceeding in the commonwealth.
Massachusetts Legal Code