I have used very specific terms in answering your question and you are not getting it. The original birth certificate will ALWAYS have your husband's name on it. If there are no amendments to it, it remains the official birth certificate whether or not the child uses another name. Since paternity was handled in some legal fashon in the divorce your husband no longer has any rights. If the bio dad, who is now the legal father wants his name on the birth certificate, he can petition the court to amend the birth certificate to put his name on. Apparnetly all your husband was interested in at the time was not paying child support and not what the birth certificate said.