Is it rude??

Eboni
I thought baby showers are supposed to be private, intimate events. My uncle's wife left a voicemail that she was bringing her mother and sister to my shower. Mind you, I don't even know them. Plus, I can't hold anymore people at our venue. So I politely told her we have to save space for the friends and family. In other words, the people I actually INVITED and who already RSVP'd. Is it rude to bring extra people to this type of event? I just thought it was weird.