Massachusetts General Laws Part I. Administration of the Government (Ch. 1-182) Ch. 34A, § 7

The commission member who received the highest number of votes shall convene the first meeting of the charter commission as soon as possible but in no event later than fifteen days after certification of the results of the state election by the governor and governor's council. If said member does not act, the state secretary shall designate another member of the charter commission to convene the first meeting. At that meeting the charter commission shall promptly organize by the election from among its members of a chairman, a vice chairman, a treasurer and a clerk and shall file a notice of such organization with the secretary of the commonwealth. If no notice of organization is received by the state secretary within twenty-four days after the organizational meeting he shall designate a charter commission for such purpose. A charter commission shall continue to exist until thirty days after the election at which its charter adoption or revision proposal, if any, is required to be submitted to the voters under this chapter or until thirty days after submission to the state secretary of a final report recommending no new charter or revision.

If any member dies, resigns or ceases to be a registered voter of such county or the district of such county from which such member was elected, or if there is a failure to elect any member, the remaining members of the charter commission shall fill the vacancy by choosing a registered voter of such county or district, respectively. The commission may continue to act notwithstanding the existence of any vacancy. Members shall serve without compensation but shall be reimbursed from the commission's account for expenses lawfully incurred by them in the performance of their duties.