Mich. Comp. Laws § 15.583

Sec. 3. (1) A public employer shall not provide medical benefits or other fringe benefits for an individual currently residing in the same residence as a public employee, if the individual is not 1 or more of the following: (a) Married to the employee. (b) A dependent of the employee, as defined in the internal revenue code of 1986. (c) Otherwise eligible to inherit from the employee under the laws of intestate succession in this state. (2) A provision in a contract entered into after the effective date of this act that conflicts with the requirements of this act is void.