I want to add my married name to my daughters birth certificates. I will not be changing their last name from the biological father, just adding my last name. How do I go about this and do I need permission from the biological father to do this? He has never seen his daughter and we don't know where he is. How does this work?
Thanks so much for whatever help you can offer...

I'm not sure where you are, but if you're in canada you'll need to go to a court house. Also, yeah you will need his permission.