Cat peeing on everything!?

I found a 1 yr old orange tabby male, Otis, in 2004. He has been the best cat ever. I bought a pal for him in 2005, an 8 week old female tuxedo kitten, Sydney. They have been great, playing, grooming each other, curled up sleeping together. Then I found a 1 yr old brown tabby female, Dixie, in 2006. She was such a sweet cat to me and my family it & was so cold so I had her checked out by the vet and I brought her in. I introduced them as the vet recommended. She attacks Sydney and hisses and bats at Otis (still does 3 years later, it has not calmed down). She has made Sydney hide most of the time and now Sydney doesn't even want anything to do with Otis. She growls at him now and they used to be best buds. Dixie has also peed in my daughter's bed, on my kid's toys, and in my dining room. It doesn't seem to matter what I do with food, litter, etc., she finds a new place to pee. I recently found another kitten, a gray tabby female, 4 months old, Cie, who Otis and Sydney don't seem to mind but of course, Dixie attacks. It will break my heart but is it time to re-home Dixie & recommend her to a one animal home? I've tried to put up with her as long as I can for nearly 3 years but we have had to rip up all of our carpet and replace with wood flooring she has peed on it so much and it's not safe and she seems to be the only one with a problem. All my cats are healthy, neutered or spayed, declawed, vet checked and indoors. I love her, she is a sweet animal to people, she just hates other animals and pees on everything. Will Sydney ever go back to her old self if Dixie's gone? Is there anything else I should try before giving her up? Thanks!