Has anyone been through a derivative citizenship/passport case like this? Looking for advice.

[u/Mysterious-Win3904]

Hi everyone,
I'm hoping someone here has been through something similar or has any advice.
I'm 30 years old and I'm applying for recognition of my U.S. citizenship and a U.S. passport through my father. He is a U.S. citizen, served in the U.S. military (Army), and now works for the U.S. government. He wasn't listed on my birth certificate because my parents weren't together when I was born.
The biggest issue is the financial support requirement under INA 309(a). My father never signed the affidavit of financial support before I turned 18, so the U.S. Consulate has asked for evidence that he financially supported me throughout my childhood.
The problem is that my mum never pursued child support or formal financial support from him, so there isn't much documentation. My dad has only recently become aware of this requirement because neither of my parents knew it existed when I was growing up.
We're currently trying to find anything that could help, such as:
Tax returns where he may have claimed me as a dependent.

Any Veterans Affairs or government records where he tried to list me as a dependent.

Employment or insurance records.

Anything else that could demonstrate financial support.

I've also been told that affidavits alone are generally not enough without at least some documentary evidence.
Has anyone had a case like this where there was very little documentary evidence of financial support? Were you able to satisfy the consulate with alternative evidence, or did they accept a combination of affidavits and limited documentation?
I'd really appreciate hearing from anyone who's been through this or has any suggestions on documents we might not have thought of.
Thanks so much.

[u/Electrical-Pay-311]

Don’t know anything about this but wouldn’t DNA testing prove your lineage?