Well just like my state of New Jersey,Pennsylvania,is the same to get a low cost lawyer the first place to start is (Legal Aid) some lawyers so Pro-bono (Free).
If the mother is willing to sign the children over to u with out a fight u can have here put it in writing n-u both sign it that is a legal contract that u can use when u take it to court as prof between u-n the children’s mother,but u have to be sue that u make sure everything u want in that written agreement is in it before u both sign it n if possible get it notarized.