Hands foot mouth exposure

So my husbands brother is military and he rarely gets to see him or his wife and kids. His brother had a child (boy) 7 months ago that my husband has seen once so far. My brother in law also has a 5 year old step son. So his new son is his first blood child and the first blood grandchild of the three brothers in the family. My husband and I had a baby two months ago. We all knew they were coming in town this week and very excited to get the new kids together etc and see each other. It's my husbands first son also. Well a day before they leave to come down his brothers son breaks out with hands foot mouth disease. Which is very contagious and can be really bad for babies because when the Sores get in their mouth and throat sometimes they stop eating then have to be hospitalized for fluids etc. he's had fevers and is currently contagious. If my two month old were to get it it could be pretty rough and bad for him. Instead of keeping the baby and herself up at her moms house 2 hours away and just letting my husbands brother come see his family... His wife decides she's coming and bringing their contagious son to stay at his mom and dads for like a week. Mind you my kids are up at their house often and his mom watches our kids for us to work sometimes. The CDC states the entire house should be sanitized before other kids especially babies are in the environment. So my kids can't even go up there for awhile and that's ok and everything I guess even though I think it's dumb of her to bring her sick and contagious child in other people's houses etc. but now my husband despite me informing him about the virus.. Still wants to take our baby up there in the house with their baby. He says they won't touch anything but his brothers damn wife has been using all of our babies stuff up there. The changing table and pack and play he sleeps in when there and toys etc. it just angers me. I'll be working Friday and he is taking him up there in the house. Adults can carry the virus also and have symptoms like a common cold but give the virus to babies and unknowingly pass it to others. So his brother and sister in law etc will be holding our child also.  It just pisses me off. I've informed his mom about this and she doesn't like it but takes a passive approach and won't say anything to her sons. Advice or opinions? I am a health care professional also btw.