Mich. Comp. Laws § 81.9

Sec. 9. After the incorporation of the village as a city as aforesaid, the government and affairs of the old or village corporation shall continue and proceed as before, and all village officers shall remain in office and exercise their powers and duties as village officers, except as herein otherwise provided, until the city officers and members of the council first elected under the new corporation shall enter upon the duties of their offices.