Mich. Comp. Laws § 45.631

Sec. 11. A county becoming a county juvenile agency in accordance with this act does not affect existing agreements between the family independence agency and private providers, which are guaranteed enforceable at the per diem rates as of the effective date of this act. This section shall not limit the powers and authority granted under this act to a county juvenile agency, including the discretion to select and contract with providers of juvenile residential care.