Actually, if the kittens appear healthy, I wasn't going to worry too much about letting them get acquainted around the place. They'll undoubtedly at least see, even if I don't let them touch, our old cat.
I'm more concerned about watching damage ~to~ them from the other kitty, and watching the dogs carefully, than I am them bringing something in with them. They've been at a home and been nowhere else yet, so I don't picture them being likely candidates for disease.
How old are the kittens, and have you been told anything about their current owners/home?