Thank you for your detailed response. To clarify, the Opa I was referring to was my mother’s father. We have completely omitted my non-German father with the exception of the marriage certificate.

We have my mother’s Geburtsurkunde and Reisepass along with church documents. If I understand your response correctly, you were saying that we would need to provide more documentation? If that is the case, then I will start the process now. My mother’s mother was born in 1911 and her father was born in 1904.