If the Board of Adjustment lacks a quorum because any of its regular or alternate members is prohibited by N.J.S.A. 40:55D-69 from acting on a matter due to the member's personal or financial interest therein, Class IV members of the Planning Board shall be called upon to serve, for that matter only, as temporary members of the Board of Adjustment. The Class IV members of the Planning Board shall be called upon to serve in order of seniority of continuous service to the Planning Board until there are the minimum number of members necessary to constitute a quorum to act upon the matter without any personal or financial interest therein, whether direct or indirect. If a choice has to be made between Class IV members of equal seniority, the Chairman of the Planning Board shall make the choice.