RFE for I-130 for father

[Pat44]

Hello All,
I recieved rfe on the I-130 applicaiton I submitted with my father as the beneficiary. It says

"If the petitioner was born in wedlock, submit the marraige certificate for the petitioner's natural parents. The marriage certificate must show that the marriage was registered or recorded by civil authorities after the marriage ceremony took place. Also, if either or both of the childs's natural parents were previously married, submit evidence of the legal termination of all prior marriages before theor marriage occurred"

Issues:
My father does not have a marriage certificate.
My mother passed away 15 years back.

My dad submitted an affidavit stating that he got married to my mother according to Hindu Rites on <date> and that at that time there was no need to register the marriage, hence is not registered with the Registrar of Marriages.

Does any one had to deal with this situation of absence of marraige certificate and what can I send more.
I have submitted the above affidavit from my father
My mother's death certificate, noting that she is wife of my father
And my birth certificate with my father's name on it.

Pelase help!!

Thanks.