(a) Except as otherwise provided in section 1074 of this title, a Vermont court may not exercise its jurisdiction under this subchapter 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 chapter, unless the proceeding has been terminated or is stayed by the court of the other state because a Vermont court is a more convenient forum under section 1077 of this title.

(b) Except as otherwise provided in section 1074 of this title, a Vermont court, before hearing a child custody proceeding, shall examine the court documents and other information supplied by the parties pursuant to section 1079 of this title. 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 chapter, the Vermont court 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 chapter does not determine that the Vermont court is a more appropriate forum, the Vermont court shall dismiss the proceeding.

(c) In a proceeding to modify a child custody determination, a Vermont court 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: