K.W.
Ok. I have an 18 month old and we also live with my parents and in the same situation. My son has called my mom "mama" a couple times before and it has really upset me. I just tell him no that's mammy not mama. Well, i finally got tired of them raising him and second guessing what I tell him so I sat down with my mom and told her straight up that I didn't feel like he was even my son. She understood and now she even asks me if it's ok if she takes him somewhere or feeds him something different, and all sorts of things now that normally they would do without even caring about my opinion on it. Just tell your parents how you feel without getting upset and starting a fight. They had their time already to raise kids and now it's your turn.