I think it's appropriate to ask people in your house to wear masks especially since it's not a masquerade party and you have reasons to do that. Just if you or your husband don't feel comfortable asking people about doing it give them a short explanation why you want them to wear a mask. I'm sure your guests are good people and will listen to you ❤️ And don't worry about your husband, sometimes we all can be people pleasers and avoid asking others of doing something 😆
They can respect your boundaries you have in place for your health or they can find other accommodations. Air bnb is a thing and hotels still exist, if you're staying for free you respect what people set as boundaries in their home or you can pay to stay elsewhere and do whatever you please.
Sht if he won’t ask em, you do it! & explain 2 them why. He should care more & be understanding of your condition. & they should all respect your boundaries as I’m sure you’d respect their’s! If they get upset, they can pay 2 stay elsewhere. I wouldn’t mind tbh. Like you said, y’all are doing them a favor.
If they can't understand your feelings then they should stay somewhere else. Its understandable they are in a situation that's unfortunate but It's important to keep your babies safe. How is it not the same as you asking your mil? Airplanes are like incubators. Who knows when they could bring with them. But just take a deep breath and take some vitamins before they arrive even if they wear a mask.
It's your home and your health and baby at risk