Mich. Comp. Laws § 331.1213
Each corporation and subsidiary corporation organized or existing under this act shall be a body corporate with power to sue and be sued and to adopt an official seal and alter it at its discretion. A debt, claim, liability, corporation obligation, note, bond, or other obligation incurred by a corporation or a subsidiary corporation after the effective date of this act shall not be a liability or debt of or enforceable against the county, except as specifically otherwise provided by written agreement of the county approved by its board of commissioners. A debt, claim, liability, corporation obligation, note, bond, or other obligation incurred by a subsidiary corporation shall not be a liability or debt of or enforceable against its parent corporation or another subsidiary corporation nor shall any debt, claim, liability, corporation obligation, note, bond, or other obligation incurred by a corporation be a liability or debt of or enforceable against its subsidiaries, except as specifically otherwise provided in writing duly authorized by the corporation or subsidiary corporation charged.
MCL 331.1213