I haven’t reported on Millie in a while, and I am pleased to write that she is doing well (even though writing or saying something like that usually leads to a tremendous upset or regression in health and behaviour.)
She has experienced three steps forward. One, is that she spends more time beside me and, sometimes, on my lap, while I am sitting in the cat-room. We spent another evening watching a movie together, and Mills was next to or on me for about half an hour. It may take some time for her to reach this stage when she is adopted, but it will happen. In fact, I have noted that because such things occur in foster-homes, they usually occur sooner in subsequent permanent homes. It’s as if the tests of any new behaviour have already been performed, and may later be skipped.

Two, it has been a long time since Millie has wet outside the litter-box. I tentatively attribute this blessing to a couple of factors: clay litter (specifically, Dr Elsey’s Cat-attract) and fewer visits by the other beasts. I can’t determine for certain that Millie is using the litter-box because of the litter in it, but she has a pair of boxes to use in the cat-room; the organic corn-based litter is almost always ignored. Is it clay in general or the brand in particular that is working for her? When she is adopted, I will strongly recommend a continuance of the same brand I am using. Why spoil success?
As well, though some of the other cats penetrate the cat-room, I chase them out. I know they should be allowed in, but when they were, Millie continued or reverted to wetting outside the box. Too many strangers in what she considers her safe-space may have given her stress beyond endurance. They have the whole house to roam in; excluding them from one room won’t destroy their sense of adventure.
Three, Millie herself is coming out of the cat-room more often. When I can - usually when the cats are snoozing on a weekend afternoon - I open the cat-room door and Mills will frequently hurry out and explore. Sometimes she doesn’t go far, but the fact that she comes out at all is significant. Equally so is the fact that she will come out when she knows other cats are loose. In such an instance, she returns to the cat-room almost at once. But again, there is significance in her action.
Hopefully, these steps continue. Will they lead to more? Possibly, though she may have come to a natural limit in what she feels can be accomplished in the Cosy Cabin. Time will tell; time and her own resolution. Those two factors are all that Millie needs.