How do my fiance and I nicely tell people not to touch our baby.? Without feeling like I'm playing favorites.

My mom is very special to me. She had my brother at 30 weeks and understands if I ask her not to touch my son or if I'm okay with it knows to wash realllyyyyy good. Because she's been there. But she asks if she can rather than just doing it.

But the rest of my family don't understand I don't guess. My aunt was present at a care time and got to touch his foot. My fiance was there and allowed it. I was totally fine with it. But I guess she posted on Facebook about touching him and my step mom saw it. When she came I mentioned washing up to the elbows in hot water before coming in whether you touch him or not. She said with an attitude, Oh I'll be touching him. I really didn't want her or my dad to touch him.

How would I go about asking visitors not to be touching him even though they have at previous visits? I don't want them to take it personal.