The presiding probate judge in each county shall appoint 2 persons and 2 alternates for those persons residing in that county to serve on the commission when the commission considers municipal boundary adjustments for territory lying within his or her county. One appointee and his or her alternate shall reside in a township, and 1 appointee and his or her alternate shall reside in a city. If there is no city in a county at the time of the filing of a petition for a municipal boundary adjustment, the presiding probate judge shall appoint 2 county members and alternates from the county at large. Within 30 days after notice from the commission that a municipal boundary adjustment is pending in the county and the office of 1 or more of the county members is vacant, the presiding probate judge shall make original appointments and any appointment to fill a vacancy. A county member shall serve for 3 years and until his or her successor is appointed and qualified. Notwithstanding the appointment and qualification of a successor, a county member shall continue to serve until the conclusion of all boundary adjustment matters which were filed during his or her term or the filing of which gave rise to his or her appointment. If a municipal boundary adjustment involves territory lying in more than 1 county, the county members of the county in which the greater part of the territory to be included within the adjusted boundaries lies shall serve on and be voting members of the commission. A county member shall receive per diem and expenses as authorized and paid by the county board of commissioners when serving on the commission on matters involving territory within his or her county. A county member shall qualify by taking and filing the constitutional oath of office.