The County Executive of Prince George's County, subject to the approval of the County Council, by a vote of a majority of the full Council, and the County Council of Montgomery County, subject to the approval of the County Executive as provided in this title, shall each designate a member for the position of chairman or vice-chairman. Upon designation by the Montgomery County Council, the name of the designee shall be delivered within three days to the Montgomery County Executive who within 30 days thereafter shall either approve or disapprove the designation. In the event that the County Executive disapproves a designee, he shall return the name of the designee to the Council with the reasons for his disapproval stated in writing. The Council, by the affirmative vote of 6 of its members, may designate a member of the Commission for the position of chairman or vice-chairman over the disapproval of the County Executive. Any designation which has not been disapproved by the County Executive in this manner shall be deemed to have been confirmed. The Commission shall elect a chairman and vice-chairman from those members designated as above. The chairman shall preside at meetings of the Commission and perform the other customary duties of the office. The vice-chairman shall preside in the absence of the chairman. The chairman and the vice-chairman of the Commission also serve as chairmen of their respective county planning boards, as constituted in this article.