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Not the same position as yourself, but I got divorced and last year changed everything back to maiden name. I didn't change my kids names (as much as I'd like to, I can't bring myself to do it and also, their dad is a great guy and don't want to take his name from them).
New bub will carry my maiden name, not DF's, however ill be changing his/her name once we are married. I have been told its hard to change a child's name though. My name was easy to do and didn't need to submit anything to BDM, just show my birth, marriage and divorce paperwork.