When any party to any instrument is dead or absent from the State at the time when registration of the instrument is required—
(a) the executor or administrator of that person; or
(b) the attorney constituted under a power of attorney of the absent party; or
(c) if the registrar is satisfied that the signature of a party cannot for any other reason be obtained, the registrar;may, in place of a party referred to in the preceding section, sign the copy instrument, and such signature shall be valid to all intents and purposes as if such copy had been signed by the original party to the instrument.