Kids at baby shower?

Mia

My mom is giving me a baby shower. Invites went out. Invitees were addressed on the envelope. My husbands family keeps calling to RSVP and they say they are coming and bringing their daughter/daughters ( who were not invited). Spoke to my MIL about it and she isn't willing to call them and tell them that this is adults only and unfortunately kids are not invited. I find this so rude, to assume that you can just bring along ur kids. These kids range in age from 4-16! So my mom is going to need to pay for extra plates since it's a per person seated dinner. And not one person on my side of the family is calling just assuming they can bring their kids along. How do I fix this?!?

*****Based on the responses maybe I should have clarified better that this is a formal sit down 4-course dinner at a venue. Similar to a small wedding. Over a hundred people were invited. So me thinking it was clear enough to only put the invitees name on the invitation seemed sufficient. If I wanted the family I would have specified "and family" on the invite. Also, maybe there are different rules for different parts of the country. But thanks for all the insensitive judging!

If anyone else is interested in this topic.....

https://community.babycenter.com/post/a34999582/is_it_rude_to_bring_your_baby_to_someone_elses_baby_shower

https://forums.thebump.com/discussion/3711988/rude-to-take-baby-to-a-baby-shower

https://www.momdot.com/is-it-ok-to-take-my-child-to-a-babyshower/

Guess I'm not alone!