Whenever a vacancy for an officer occurs in headquarters, South Carolina Air National Guard, it must be filled from among the officers of the South Carolina Air National Guard who are considered best qualified to fill the vacancy by the chief of staff, headquarters, South Carolina Air National Guard, and the Adjutant General. Assignment of an officer to headquarters, South Carolina Air National Guard, does not entitle him to promotion without regard to seniority rights specified elsewhere in this chapter. Position vacancies for enlisted personnel in headquarters, South Carolina Air National Guard must be filled as directed by the chief of staff, headquarters, South Carolina Air National Guard, subject to approval of the Adjutant General.