) Except as otherwise provided in section 39204, the Superior Court of Guam may not exercise its jurisdiction under this Article if, at the time of the commencement of the proceeding, a proceeding concerning the custody of the child has been commenced in a court of another State having jurisdiction substantially in conformity with this Act, unless the proceeding has been terminated or is stayed by the court of the other State because the Superior Court of Guam is a more convenient forum under section 39207.

(b) Except as otherwise provided in section 39204, the Superior Court of Guam, before hearing a child-custody proceeding, shall examine the court documents and other information supplied by the parties pursuant to section
39209. If the court determines that a child-custody proceeding has been commenced in a court in another State having jurisdiction substantially in accordance with this Act, the court of Guam shall stay its proceeding and communicate with the court of the other State. If the court of the State having jurisdiction substantially in accordance with this Act does not determine that the court of Guam is a more appropriate forum, the court of Guam shall dismiss the proceeding.

(c) In a proceeding to modify a child-custody determination, the Superior Court of Guam shall determine whether a proceeding to enforce the determination has been commenced in another State. If a proceeding to enforce a child-custody determination has been commenced in another State, the court may:

(1) stay the proceeding for modification pending the entry of an order of a court of the other State enforcing, staying, denying, or dismissing the proceeding for enforcement;

(2) enjoin the parties from continuing with the proceeding for enforcement; or

(3) proceed with the modification under conditions it considers appropriate.