My wife and I are married with 2 children now, but she has a child before getting married. He is 7 and the father is in jail. His name was on the birth certificate but the child's last name is the still the mothers maiden name. They where never married. We are in the philippines so I don't know how the rules work here..

Best bet is to contact an attorney.

Yes, you can do adoptions without an attorney--but you can set a bone without a doctor, too, and no one even THINKS about doing that.