The Board of Supervisors may authorize the inclusion of additional member municipalities in the District upon the terms and conditions it, in its sole discretion, shall deem to be fair, reasonable, and in the best interest of the District. The legislative branch of any nonmember municipality desiring to be admitted to the District shall make application for admission to the Board of Supervisors of the District in the form and manner that the Board shall determine appropriate. The Board shall determine the effects and impacts which are reasonably anticipated to occur in the event such municipality is admitted and shall thereafter either grant or deny authority for admission into the District by the petitioning municipality. If the Board grants such authority, it shall also specify any terms and conditions of said admission, including the financial basis upon which such admission is predicated. The petitioning municipality shall thereafter comply with the approval procedures specified in 24 V.S.A. chapter 121. At such time as a majority of the voters of the petitioning municipality present and voting at a meeting of the municipality duly warned for such purpose shall vote to approve the agreement and the terms and conditions for admission, the vote shall be certified by the clerk of the petitioning municipality to the Board of Supervisors of the District. Thereafter, upon compliance by the petitioning municipality with the terms and conditions of admission, the municipality shall, by resolution of the Board of Supervisors of the District, become and thereafter be a member municipality of the District.