I won't name the baby after him. HELP 😰

Kristin
So The baby's dad wanted me to name the baby after him, and I said no. His name is a family name. For example his name is John, his fathers name is John and his grandfather, so on... well I don't like the idea of mulituple people having the same name. Because of this he's told me I can name the baby whatever I want. Which is fine. But his family is set on me naming the baby John. His sisters just assume I am. I'm not sure how to tell everyone no without people being upset with me. His mother even said "You're going to name him John" and saying I'm not allowed to name him anything else. It's really overwhelming. I've already decided I'm using John as the middle name which I thought was a nice compirmise. I just don't know how to tell them.