Tell me if I'm wrong !

 So my mother and Aunty have been planning my shower. My mother has continued to invite people I don't know saying " oh they're your cousin" I say yea okay, don't know them but since she has spent most money I just let it go. Now my grandmother, who I love dearly I'm just not close to her. She put my mom in a situation to invite a cousin I do know but have no good relationship with for her own personal reasons. I said no she can't come, my mother who doesn't get along with her or her mother believes I should just let her come. I still say no, we have too many people and limited room. Also I'm upset that she even think it's okay for a guest( my grandmother isn't planning or really apart of this event) to invite someone if she so choose. I'm I wrong to feel this way?