My friend and I are thinking about getting an apartment together. I have two neutered male cats that are less than a year old and her neutered cat is about 12. Does anyone have experience with introducing young cats to old cats? I think my cats will play with each other and not harrass the older cat too much, but who knows? Also, my cats have been dealing with uris and probably have the herpes virus. My friend has no idea the last time her cat got vaccinated. If her cat repeats the 3 FVRCP/distemper vaccines, should he be pretty safe from contracting herpes from my cats? I know they're not 100% effective, but pretty close, right?