Sending snowflakes your way!
We have a lot of RSV here too...my cousin's preemie ended up back in the hospital with it and apparently there were 68 babies admitted!
I totally understand about the germ thing. Last time DH seemed to think I only told his family wash up before touching my baby...but really, my family just knew to do it and I didn't have to say anything.
I say just don't back down, any sort of coughing, sneezing, sniffling and say hands off the baby. Who cares if they are upset with you -- it's your job to keep your baby safe, not theirs. They'll get over it and if not, maybe they won't visit anymore
When DS was just a few weeks old, I heard my MIL blowing her nose and sniffling/coughing for quite awhile in the morning as she was getting up. I told her she couldn't hold DS, and she started getting all defensive saying she wasn't ill, it was just her sinuses draining like they always do. Too bad for her, she didn't hold him. I should have told her, next time stay at a hotel and I won't hear your mucous draining...hehehe. (Actually this time they are required to stay in a hotel, no way am I having houseguests for the first few months - at least!)