As provided in MGL Chapter 40A, Section 9, the Planning Board, when acting as a Special Permit Granting Authority, may appoint an alternate member to serve in such time that an elected member of the Board is unable to serve. Such appointment shall be by an affirmative vote of four of the five elected members of the Planning Board. The Planning Board may make such an appointment at any time; provided that, regardless of the appointment date, the term of each such appointment shall expire at the beginning of the first regularly scheduled Planning Board meeting that takes place after the next general Town election following that appointment. Planning staff, as well as members of the Board of Appeals and Board of Selectmen may not concurrently serve as the alternate member for the Planning Board. In the event the alternate is unable to fill out the appointed term, the Planning Board shall appoint a replacement within 30 days. The replacement shall serve the remainder of the unexpired term.