An alternate member of the Board, during the absence of a member from the same group (domestic manufacturer, importer, or public member) and region (as applicable) may serve in the place and stead of such member and perform such duties as assigned. In the event that both a member of the Board and the alternate are unable to attend a meeting, the Board may not designate any other alternate from a different group or region to serve in such member's or alternate's place and stead for the meeting.