Twinkle (the name that K and I have more or less settled on - though Tinkerbell and Buttercup are still possibilities that we discuss) has gained some degree of grudging acceptance from Patch, as you can see from the photograph. Iffy is still growling, hissing, and gurgling (yes: she makes that noise) a storm when Twinkle gets too near. Or within line of sight, actually.
Packrat and Ondine came over to see Twinkle just now, and she behaved admirably. The other two cats were grouchy rotten.