It's not weird. It's just a name really. Since you changes your name, it now belongs to you so you can give any of your babies that name. Make sense? It's a relationship to you because that's your name now, nothing to do with your ex.
Personally i wouldn't do it. I think baby should have the biological fathers last name (even if he doesn't want to be involved) or your maiden name. It does seem a bit weird especially if you are getting a divorce.
My mom gave my brother her maiden name even though she still has my dads last name. Just an idea.
If you plan on keeping your married name as your last name then that is definitely the best thing to do. :-)
I don't see y not it is still ur last name and ur other kids last names and if the other guy doesn't want the baby who cares what u name it :)