Michigan Compiled Laws, Chapter 700. Estates and Protected Individuals Code § 700.3202

Sec. 3202. If conflicting claims as to the decedent's domicile are made in a formal testacy or appointment proceeding commenced in this state and in a testacy or appointment proceeding after notice pending at the same time in another state, the court of this state shall stay, dismiss, or permit suitable amendment in the proceeding in this state unless it is determined that this state's proceeding was commenced before the proceeding elsewhere. The determination of domicile in the proceeding first commenced is determinative in this state's proceeding.