Upon the receipt of a notice that the proposition has been adopted as provided in section 70.050, the presiding commissioner of the most populous county, as determined by the last federal decennial census, shall call a meeting of the county commissions of all the counties voting on the proposition, at such place and time as he may designate. Unless otherwise provided by law, the respective county commissions sitting as a body, with each county commissioner having one vote, shall proceed to administer the function, service or common employment of the county officer or employee and allocate the costs among the counties. Any county that has voted to participate in a joint undertaking as provided in sections 70.010 to 70.090 is hereby authorized to issue bonds, as provided by law for the issuance of county bonds, for such purposes.