Section 452.765 - Simultaneous proceedings1. Except as otherwise provided in section 452.755, a court of this state shall not exercise its jurisdiction under sections 452.740 to 452.785 if, at the time of the commencement of the proceeding, a proceeding concerning the custody of the child had been previously commenced in a court of another state having jurisdiction substantially in conformity with sections 452.700 to 452.930, unless the proceeding has been terminated or is stayed by the court of the other state because a court of this state is a more convenient forum under section 452.770.2. Except as otherwise provided in section 452.755, a court of this state, prior to hearing a child custody proceeding, shall examine the court documents and other information supplied by the parties under section 452.780. If the court determines that a child custody proceeding was previously commenced in a court in another state having jurisdiction substantially in accordance with sections 452.700 to 452.930, the court of this state 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 sections 452.700 to 452.930 does not determine that the court of this state is a more appropriate forum, the court of this state shall dismiss the proceeding.3. In a proceeding to modify a child custody determination, a court of this state shall determine if 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.