Re: Changing My Child's Name with No Father Named on the Birth Certificate
one of the regulars here refers to this as a backdoor adoption. Courts do not like backdoor adoptions. You will have to attempt to contact the presumed father when attempting to change the name. Since it was too expensive when trying to adopt, it will be too expensive now.
adding a name or hyphenating would require the same actions as just changing her name.
I am not an attorney and any advice is not to be construed as legal advice. You might even want to ignore my advice. Actually, there are plenty of real attorneys that you might want to ignore as well.