Except as provided in paragraph (2) of this subsection, the Commission shall adopt a plan by resolution with the affirmative votes of at least six commissioners, of whom at least three shall be from Montgomery County and at least three shall be from Prince George’s County. To adopt an area master plan or a functional master plan that lies entirely within one county, the affirmative votes of three commissioners from that county shall suffice to adopt the plan. The resolution to adopt a plan shall refer expressly to the maps and the descriptive and other matter that the Commission intends to form the whole or part of the plan. Any action taken shall be recorded on the map, plan, or descriptive matter by the identifying signature of the chair and secretary–treasurer of the Commission.