need some help with my parents

OK sorry I am the youngest of 3 girls and I'm I recently announced that I'm giving my parents their 1st grand kid. I currently live out of state and my parents were helping me with my rent however now that my boyfriend and I have a child on the way we were going to move in together and raise the kid together. My mother insist on me moving back home away from my boyfriend and having the kid there. With my job I am able to cover everything with the insurance and the new rent how do I convince my mother that this is the best thing for me and my new family. My dad is totally on board with whatever decision they make however my mom seems to really want me to come home.