Gee, I can see where you are at your wits end. I would be too after 4 years of one peeing all over my house. Is there anyway you could just put her out of the house and make her an outside cat? I would not judge or criticize anyone for doing what they have to in a case like this.. I know you have done and tried everything possiable to fix the problem and when she has the rest of them doing it, you HAVE to do something and do it fast!