Mich. Comp. Laws § 600.5355

Sec. 5355. All notices provided for in this chapter may be given by registered mail with return receipt demanded, and if the return receipt is not received the court may order the same served as process is served in said court, and the cost thereof shall be paid by the petitioner. When and if the petitioner changes his employer he shall notify the clerk of the court and execute a new assignment of his wages and the clerk shall notify the new employer.