If the Registrar or a person appointed to assist such Registrar is disabled from performing his duties or for any reason vacates his office or leaves his jurisdiction or dies, then—
(a) in the case of the Registrar, the 3[Special,] Additional or Joint Registrar, in the office of the Registrar, and
(b) in the case of a person appointed to assist the Registrar, the senior most officer holding the next higher post, in the respective office, shall, unless other provision has been made in that behalf, hold temporarily the office of the Registrar or, as the case may be, of the person appointed to assist the Registrar in addition to his own office and shall be held to be the Registrar or the person appointed to assist the Registrar under this Act, until the Registrar or the person appointed to assist the Registrar resumes his office, or until such time as the successor is duly appointed and takes charge of his appointment.]