Ohio Rev. Code Ann. § 3127.20 – Custody proceeding pending in another state

(A) Except as otherwise provided in section 3127.18 of the Revised Code, a court of this state may not exercise its jurisdiction under sections 3127.15 to 3127.17 of the Revised Code if, at the time of the commencement of the proceeding, a child custody proceeding concerning the child is pending 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 court of this state is a more convenient forum under section 3127.21 of the Revised Code or a similar statute of the other state.
(B) Except as otherwise provided in section 3127.18 of the Revised Code, a court of this state, before hearing a child custody proceeding, shall examine the court documents and other information supplied by the parties pursuant to section 3127.23 of the Revised Code. If the court determines that a child custody proceeding is pending in a court in another state having jurisdiction substantially in accordance with this chapter, 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 this chapter does not determine that the court of this state is a more appropriate forum, the court of this state shall dismiss the proceeding.
(C) In a proceeding to modify a child custody determination, a court of this state 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 do any of the following:
1. (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. (2) Enjoin the parties from continuing with the proceeding for enforcement;
3. (3) Upon the demonstration of an emergency, proceed with the modification under conditions the court considers appropriate.