Wis. Stat. § 938.15: Jurisdiction of other courts to determine legal custody.

Except as provided in s. 938.028 (3), nothing in this chapter deprives another court of the right to determine the legal custody of a juvenile by habeas corpus or to determine the legal custody or guardianship of a juvenile if the legal custody or guardianship is incidental to the determination of an action pending in that court. Except as provided in s. 938.028 (3), the jurisdiction of the court assigned to exercise jurisdiction under this chapter and ch. 48 is paramount in all cases involving juveniles alleged to come within the provisions of ss. 938.12 to 938.14.