Massachusetts General Laws Part II. Real and Personal Property and Domestic Relations (Ch. 183-210) Ch. 190B, § 5A-209

(1) If the court in the commonwealth has jurisdiction under section 5A-203, it may proceed with the case unless a court in another state acquires jurisdiction under provisions similar to section 5A-203 before the appointment or issuance of the order.

(2) If the court in the commonwealth does not have jurisdiction under section 5A-203, whether at the time the petition is filed or at any time before the appointment or issuance of the order, the court shall stay the proceeding and communicate with the court in the other state. If the court in the other state has jurisdiction, the court in the commonwealth shall dismiss the petition unless the court in the other state determines that the court in the commonwealth is a more appropriate forum.