Mich. Comp. Laws § 600.3160: Persons other than mortgagor or vendee securing debt.

Sec. 3160.

If the land contract or mortgage debt is secured by the obligation or other evidence of debt of any other person besides the vendee or mortgagor, the plaintiff may make that person a party to the action, and the court may order payment of the balance of the debt remaining unsatisfied, after a sale of the mortgaged premises, against this other person as well as against the vendee or mortgagor, and may enforce this judgment as in other cases.