well let me tell you, I have been through my share of crap concerning things similar and I also used to type up birth certificates in a maternity ward. If at the time of birth the mother was married to this guy she's married to now, the child would have to have his name even he was not the father, that's the law! and also you are not legally responsible for anything right now unless ordered by a judge. the person whose name is on the birth certificate is responsible and you all are gonna end in court over this, trust me....