In any district that has adopted the provisions of this article there shall be appointed a personnel commission composed of either three or five members. The governing board of any community college district, by a majority vote, and with the agreement of the existing personnel commission of the district, if that commission is in existence, may elect to increase the membership of the personnel commission from three to five members or to decrease the membership from five to three members. If two or more districts are under the jurisdiction of governing boards of identical personnel, only one commission shall be appointed. In those cases this article shall apply alike to all of the districts, and the expenses of the commission shall be paid out of the general funds of all of the districts in proportion to the benefits derived therefrom as determined by the governing board.