Family tree certificate

I applied for family tree certificate, i had applied with my fathers, mother's and sister's death certificate's , my mother's death certificate had a problem and did not have my father's name in it, this is the reason why it got rejected. My mother died in 1987 and did not have a voter id, aadhar or passport, i just have my birth certificate from hospital with her name in it and my passport with her name. How am i going to convince tehsildar? Some have advised to get an affidavit or give a declaration in newspaper that i am her only surviving son, not sure what to do advise please.