The application shall also be supported by an affidavit of due execution in the following cases—
(a) where the will was executed by a testator affixing his or her mark to the will;
(b) where the will contains no attestation clause or the attestation clause is insufficient to afford evidence of due execution;
(c) where the will bears no date of execution or there is doubt as to the date of execution;
(d) where the will was or appears to have been executed by a blind or illiterate person or by another person at the direction of the testator;
(e) in any other case in which it is required by the Registrar.