Unvaccinated cousin around newborn

Mr

I don’t want this to turn into another “are vaccinations good or bad” debate. My husband and I believe in vaccines and our 2 yo son is fully up to date on his schedule (we delayed one temporarily at one point in his schedule because my FIL was undergoing chemo and his oncologist recommended it, but he has been caught up.) I’m currently 34 weeks pregnant with our daughter who is due June 5th.

I’ve recently discovered that my sister has not started any of my nephew’s vaccines (no health reasons why, she’s just anti vax). He’s currently 4 mos old, and will be almost 6 mos when my daughter is born. I’m trying to figure out where to draw the line with my daughter and my nephew coming into contact presuming my sister continues to refuse to vaccinate her son. I’m not so much worried about my son being around my nephew because he’s already two and has gotten all of the important ones including MMR.

Assuming you believe in vaccinations, where would you draw the line with your own children and family?

Do I take it so far as to not visit my parents at the same time as my sister and nephew for a period of time? Or is the fact that my nephew will only be 6 mos and not physically interacting with her protection enough as long as everyone washes their hands, etc?

Maybe I’m overreacting but I want to do everything I can to protect my little girl. I’m a little irritated that my sister is refusing to vaccinate my nephew and could potentially get my child sick as a result.