How do I make sure people who are not invited dont show to the baby shower?

What can I say that isn’t going to ruin a relationship? My boyfriends uncle has about 10 daughters. Two of them were invited to my gender reveal, it was really laid back and a FB invite but the whole family came, even some of their boyfriends.

Well my baby shower is coming up and we are doing paper invite w/RSVP but it’s at my boyfriends parents house— so still kinda laid back but more formal. It’ll be tight with my invite list as it is. How do we make sure they don’t all come again? I’m so stressed. My MIL would be the one to say something... again, only 2 of the cousins are invited and their mom (his aunt).

Also— at the gender reveal they didn’t even say hello to me. Sorry but how rude is that?!?!