Ohio Rev. Code Ann. § 3115.204
(A) A tribunal of this state may exercise jurisdiction to establish a support order if the petition or comparable pleading is filed after a pleading is filed in another state or a foreign country only if all of the following apply:
(B) A tribunal of this state may not exercise jurisdiction to establish a support order if the petition or comparable pleading is filed before a petition or comparable pleading is filed in another state or a foreign country if all of the following apply: