Okla. Stat. tit. 56, § 240.9

In filing cases involving concurrent jurisdiction between the administrative proceedings of the Department of Human Services and the district court, the cases shall be filed in the administrative proceedings of the Department of Human Services. The Department of Human Services, by regulation, may establish exceptions from this requirement subject to federal approval. Child support orders originating from other states shall be enforced to the same extent as orders originating within this state. Said orders to be filed in the county of residence of the obligor or in the county of residence of the person entitled to support.