It's only taken 10 months but we finally have an uneasy truce in the house. Tan, the cat that doesn't like other cats, had decided that she doesn't have to attack the other cats when they come out of the bedroom. And possibly even more amazing she is learning that she is NOT the boss in the bedroom and has no authority to dictate what the other cats do in their part of the house. Now this miracle of understanding does not mean Tan doesn't still chase Dewdney around the house and try to "wide foot stomp" intimidate Wilson, but it does mean it happens less often. So little so that I have officially opened the screen door.
The only exception is meal time as that is when Dewdney will finish her dinner and then go try to eat Tan's. It is a wonder that Tan chases her around the house.