If, within thirty days of the adoption of the proposal to consolidate by the initiating legislative body, the legislative body of each other unit of local government included in the proposed consolidation has accepted the proposal, or if a sufficient petition has been certified to the presiding officer of the legislative body of the town, such presiding officer shall call a joint meeting of the legislative bodies of all of the units of local government included in the proposal, designate the time and place, and preside at the joint meeting. Such meeting shall by joint resolution appoint a consolidation commission of not fewer than five nor more than fifteen members. Each political subdivision included in the proposed consolidation and the area of the town, if any, outside the boundaries of any such political subdivision shall be represented on the consolidation commission, as nearly as possible, in proportion to the number of electors residing in each such political subdivision and the number of electors residing outside the boundaries of any such political subdivision; provided there shall be at least one commission member from each political subdivision in the proposed consolidation and one member from the area of the town, if any, outside the boundaries of any such political subdivision.