Re: How to Change a Stepchild's Name
You are a guardian, not a parent therefor, this is not your daughter. I see no reason you should even consider changing the child's name and likely will not be allowed to. Does the father even know the mother is deceased? You do realize that the father has default custody of his own child when the other parent is deceased, right?
What needs to happen is the father located and told his daughter's other parent is deceased and as such, has every right to have custody of his daughter.
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.