This Is A Complex Situation

Location: Pennsylvania

A friend of mine was on survivors benefits growing up and SSDI from a very young age. The man who signed their birth certificate ended up passing away suddenly before they turned 18. Later on they met another man claiming to be their legitimate father. The person claiming this did not want to submit to paternity testing. But because they looked very simular, my friend started having suspicions with no way to prove it. Fast forward years later and they are in their mid 20s and still wondering.

The mother of the man who initially signed the birth certificate is now trying to claim my friend's benefits as fraudulent. Which means she would have had to know when signing my friend up for the benefits that there were issues with the legitimacy of the application. Even still, my friend's grandmother is threatening to push the issue and report it to social security.

What can my friend do in this situation? Do they just reach out to social security and inquire about the issue, or should they not worry about it? I believe that survivors only lasts up until the child turns 18. Which would mean that the current benefits are only SSDI and my friend did/does legally qualify for that. Do survivor benefits in PA carry over when they are older?

I'm not good with understanding how these benefits work and I really need an idea of what I need to do to help my buddy out. Any answers would be much appreciated.