Michigan Compiled Laws, Chapter 600. Revised Judicature Act of 1961 § 600.809

Sec. 809. (1) Except when the vacancy or vacancies occur after the date established by Act No. 116 of the Public Acts of 1954, as amended, being sections 168.1 to 168.992 of the Michigan Compiled Laws, for nonincumbent candidates to file for the office of probate judge for a full 6-year term or for the unexpired portion of a term, whichever is applicable, a probate court district created under section 808  1 shall become effective upon the existence of a vacancy in the office of probate judge in all but 1 of the counties comprising that district.

(2) When a probate court district becomes effective pursuant to subsection (1), the remaining incumbent probate judge in the district shall serve as the probate judge of the district until the term for which he was elected or appointed expires. Thereafter the 1 probate judge for the district shall be elected as provided in section 808(5).