Child is Residing With a Non-Parent

My question involves paternity law for the State of: PA

I have a question about a child who is not living with the biological mother but is living with a non biological father and wanted to know what should be done in this situation because it's a disaster waiting to happen & I don't want to see anyone get hurt & want to help but don't know what to do. The "father" may end up in trouble with the IRS (he has claimed the child in the past), the mother could end up in trouble for welfare fraud (IDK how she is getting away with the child having medical insurance when child doesn't live with her) and the child has orthopedic & mental health needs that are being addressed by the "father". The biological father has never paid any child support & abandoned the child who is now 6. The "father" has known he may not be the father until he took a DNA test this past year & found out for sure he is not the father. And the mother just told him after he did the DNA testing that when the child was about a year old she had DNA testing done & already knew this other guy was the father.
Mother & "father" were together when she had child at hospital the real father wasn't around. She told "father" at that time he might not be the bio dad. They stayed together until the child was 3 yo and she got caught cheating w dude she is with now. She ended up homeless & child stayed with "father." Mother got housing within a year of this, doesn't care as long as child is taken care of & doesn't want responsibility of being primary custodian. She had another child with dude who is now 3. He basically takes care of her other child while Mother works (she finally got a job this past year) & they live in a project.
The "father" & child live in a decent housing plan in a home with his mom, dad & brother (a supportive environment) & the real father has a criminal history that is extensive, being arrested on drug charges almost every year since the child has been born.
The child isn't in any danger from either the mother or the "father" who is taking very good care of him, mother does have visits with the child on weekends when she wants to, but like I said if one thing got noticed the whole situation could collapse like a house of cards. I'd appreciate advice on this please, ty

Did you have an actual question?

And who are you anyway?

If the child is being taken care of, I fail to see why you are so concerned.

If "father" was there when child was born and is on child's birth certificate (doesn't sound like you actually know, and its really none of your business anyway), then he's not "father." He's father, or just dad.

Has mom paid any child support?. She's the other legal parent in this situation, the only one we know for sure, regardless of who is legally dad. If the man who he is living with now is on the child's birth certificate, he should file to establish custody and support. Mom needs to be responsible whether she wants to or not.

But here's the best piece of advice for you: stay out of the drama.

Exactly.

The child is in no danger, and there's nothing illegal (or even vaguely wrong) about the child living whomever.

If the other legal parent has an issue with it, the other legal parent can act.