(1) At the meeting of the board of county commissioners at which the cemetery maintenance district is declared organized, as provided by section 27-108, Idaho Code, said board of county commissioners shall divide the cemetery maintenance district into three (3) subdivisions, as nearly equal in population, area and mileage as practicable, to be known as cemetery maintenance commissioners subdistricts one, two and three. Not more than one (1) of said commissioners shall be an elector of the same cemetery maintenance subdistrict. The first commissioners appointed by the board of county commissioners shall serve until the next cemetery maintenance district election, at which their successors shall be elected. Any vacancy occurring in the office of the cemetery maintenance commissioner, other than by the expiration of the term of office, shall be filled by the cemetery maintenance board.