Changing my mind? Ok or not ok?

alyssa

My 16th birthday I wanted to go to Tennessee! Supposed to be my parents, my bf, and me! Well I guess I made a mistake of “inviting” my sister and nephew (says my mom). Is it ok to change my mind about them going? And how should I say something in a nice way so I don’t come off mean? I will take any advice! Thanksss.