So for those who've asked, here's a quick update on the cat situation:
- The upstairs floor has, apparently, been ceded to the newcomers, Bill and G'Kar. D's cats rarely go up there now, except when they want to use the litter box that is up there (it was their original litter box).
- The ground floor appears to be disputed territory, but only mildly so. Each cat is willing to defend the immediate vicinity around them against cats of the opposite faction, but won't go out of their way to go across a room and chase a cat out of it, except...
- G'Kar appears to have a bit of a thing for Clementine. She'll hiss at him and make it clear she wants him to go away, but he's just all nice and polite, like the mack daddy virgin that he is. He'll follow her around the house (pissing her off more and more, obviously) until eventually she takes a swat at him and he retreats to the upstairs.
- The basement is definitely the domain of D's cats, although G'Kar and Bill have each at least once ventured down there.
- Certain spots on the ground floor are undisputedly D's cats turf -- D's office, the spot by the screen door in the kitchen, and the vicinity of their food dishes.
Overall, the hissing is usually just growling at each other as they pass, with no significant conflicts to speak of (although, that's not to say the fighting is 100% over... just two days ago, G'Kar and Gracie formed a cartoon-like ball of screaming fur for all of three seconds). But, at the 10,000' level, a state of détente appears to have formed.
Have you tried the catnip yet?
I bet it would be fun to watch.