Family Law Questions? Ask a Family Lawyer Online.
Thanks for the opportunity to assist you. MI Rule of Civil Procedure 2.103 tells us that any legally competent adult can serve a subpoena. If the person is not a professional process server or sheriff's deputy, they'll have to file an affidavit regarding service.
As for the time frame, I cannot find a rule that says a subpoena must be served within X days before the hearing. The general rule is no less than 72 hours before the hearing. Serve earlier than later.