New cat hostilities...
Just to indroduce my cats:
Max - Dominant male, he's been "done", very loving, never scratches, playful but not aggressive - doesn't like confrontation. 6 years old.
Millie - Female, also been "done", affectionate on her own terms but doesn't always get on with Max. 6 years old but no relation to Max.
Tilley - New kitten, female, not spayed yet, originally very hostile to both us and the other cats, now very affectionate and playful with us. 6 months old.
The problem: We've had Tilley for 3 weeks now, and she's settled in reasonably well after a shaky start. She gets on pretty well with Max now - they will play with eachother but haven't got to the stage of washing eachother or curling up with eachother yet. Millie however, is a different matter. Every opportunity she gets she chases Tilley all around the house, often backing her into a corner and scratching/hitting. Often she'll wait until me and my husband are out of the room, although we try not to leave them together unsupervised. Sometimes Max will intervene and bowl Millie over to stop her chasing the kitten.
I don't know how to deal with this effectively. We have introduced them as well as we can, we have Feliway diffusers, started feeding them together (which they seem happy with) and giving them equal attention etc. When Millie chases Tilley, we try and stop them (obviously) then will try and discipline Millie by shutting her in a room by herself for 5 minutes or chasing her out of the room. So far this doesn't seem to be working, she is still chasing Tilley remorselessly.
Any ideas on what we can do?