law: 7. Temporary absence of member.
  (1) If any nominated member is by infirmity or otherwise rendered temporarily incapable of carrying out his duties or is absent on leave or otherwise in circumstances not involving the vacation of his office, the Central Government or the State Government, as the case may be, may nominate another person to act in his place during his absence.
  (2) No act of the Board shall be invalid merely by reason of
  (a) any vacancy in, or defect in the constitution of, the Board, or
  (b) any defect in the nomination of a person acting as a member thereof, or
  (c) any irregularity in its procedure not affecting the merits of the case.