
Quoting
Mr. Knowitall
If the mother wants to name her child Rumpelstiltskin, that's her right. You can do whatever you want to try to do in relation to paternity, but you cannot force her to change the child's last name. It's not your child, and it's none of your business.
If you are confusing matters by suggesting that somebody you believe to be the father, but who has never previously bothered to try to establish paternity, is now going to petition the court for a declaration of paternity and a name chage, that's a different matter entirely. And changing the subject doesn't make us wrong - it just means that you changed the subject, but remain wrong on the legal issue we were addressing.
Beyond that, not that you would know, the statute underlying your conception that this person may bring a paternity action provides,
You've admitted that your husband had reason to believe that he was the father by virtue of his sexual relationship with the mother. You state that, when voluntarily acknowledging his paternity by affidavit, "at the time he had believed that the baby was his." You suggest that he had some subsequent visitation with the child. You apparently had recent access due to his continued assertion of his parental rights, during which you took a DNA sample for testing. So that pretty much rules out the notion that he never represented to others that the child was his. Obviously we're past the child's fourth birthday. So... the person you believe to be the father has quite the uphill battle on his hands.
Beyond that, for changing the child's name,
That's pretty clear, isn't it, that the court does not automatically change the child's name.
If you have any actual legal authorities to share which would affect the application of these statutes, please do share them.