Will my new husband have to adopt my daughter to give her his last name?

We need to know a bit more please. Can you tell us the bio-dad and where he is in this?

You also need to go to Court to change the last name. You need the permission of the birth father to do that.

Adoption - same thing.

I wonder why he would be interested in giving them his last name but not adopting? But the process is similar and he might as well go for adoption.