The commission is hereby empowered to cooperate with any other planning or zoning commission within Elmore County for the formation of a joint planning or zoning commission. The number of members of such joint planning or zoning commission, their method of appointment and the proportion of the cost of such regional planning to be borne respectively by the various participating governing bodies shall be such as may be agreed upon by said joint commission and the governing bodies involved. Members of joint planning commission shall be residents of the county from which appointed. (Ord. 727, 11-22-1971)