During the temporary absence of the Chief Administrative Officer or the head of an agency of the executive branch, or if such position shall become vacant, the County Executive shall make a temporary appointment to fill such position. No person shall serve as Acting Chief Administrative Officer or acting head of any agency for a period longer than sixty calendar days. Such limit may be extended an additional four calendar months by resolution of the Council. An individual may be temporarily appointed to fill a vacancy, no more than one year, without an intervening permanent appointment.