When it comes to introducing them, it might be an idea to be a bit careful.
On another BB a veterinarian said that the best way of introducing a new cat was to smear them all with tuna or sardines and sling them in the bathroom.
Older cats (IME) tend to be Ok-ish with kittens, but people might have some tips.
Tips are definately useful - last night we brought X into the room in a cat cage and just sat him down while we attempted to play a game with the other 2. After a little hissing (no growling), Milo was able to be distracted and played - we might try this again tonight, before finally letting them to meet properly over the weekend.
Morbo
But then he would give himself gas! 