Family Member certificate required to establish a relation bw 2 deceased member

Dear Sir,
Notarized Affidavit + Genealogy Certificate from Notary
If the SDM refuses to issue such a certificate, an alternative is to:

Prepare a notarized affidavit detailing the relationship.

Get a Genealogy Certificate (family tree) prepared and signed by close relatives.

This may be accepted as secondary evidence for caste or inheritance matters.

Certified Copy from Municipal Records or Old Caste Registers
If your grandfather's sister had a valid caste certificate, sometimes these records contain family lineage. You can:

Visit the issuing authority of her caste certificate.

Check if any family linkage or parental names are recorded, and obtain a certified copy.

Dear Client,
In the given scenario, when both your grandfather and his sister are deceased, then to obtain a caste certificate based on their cast is challenging. However, you may consider to apply for a Family Member Certificate which is also known as a Family Tree Certificate that contains the details of different generations of a family and the names of the family members, children and grandchildren. It is issued by the concerned Tahsildar or a land revenue officer or gram panchayat of the respective area where your grandfather was originally/permanently resided. This certificate is legally admissible and equally important for accessing the status of your caste as OBC. Once you succeed to obtain a Family Tree Certificate from the concerned authorities, you can apply for a caste certificate to the concerned authority attaching an affidavit explaining the reason behind your application for the change of caste, but it exclusively depends on the decision of the State Level Caste Scrutiny Committee. For more information and clarification on the subject, you may contact or visit the office of the said committee.