Help! Sick inlaws visiting newborn?!

My in-laws have a weird living situation. In their house is their oldest son, his wife their six kids ages 5mo to 15yr and also one of my in-laws other sons. This week the kids have started getting sick with fevers, diarrhea, and vomiting. My mother in law says she feels fine but is always holding and taking care of the kids( she's basically their second mom) So my question is , there's no way I should let anyone from that house come visit the baby until everyone has felt better for at least a week or more right?! I mean how am I supposed to tell my husband almost his whole family can't come to the hospital?! And how do I tell them they can't come?