Boundary setting w/ in laws

So you’re all already aware of my extreme covid anxiety that started when I was pregnant with #2. We’ve been so so safe this whole time and people give us so much shit for it.

Well my SIL is getting married next week and they went from a guest list of just immediate family (20) to 200 people! People must be fully vaccinated or tested prior. Masks are not required. 😳 they are guilting us into bringing our kids (almost 2 years and 6 months) because they are flower girl and ring bearer. My husband and I are vaccinated but obviously not our kids.

My MIL said she can’t wait for everyone to kiss the baby. And I said oh no way.. that’s not happening. (Our best friends haven’t even been around the baby! Thats how safe we are!) she doesn’t see what the issue is.... she also wants our 2 year old to socialize with everyone indoors. Though most of the wedding is outdoors besides dancing. At which time We will leave.

I feel like I need to set the boundary before the wedding so it doesn’t come as a surprise.. we are not ok with people being unmasked near our kids. We are staying on the property of the wedding so I will bring the kids in there if people are not wearing masks or being respectful of our asks.

how do I set this boundary kindly but sternly!? I’m trying to avoid a full blown panic attack at this wedding but my anxiety is at an all time high and I keep having nightmares about this. 😩