kitty going crazy?

all right, i am at the end of my rope! my little girl, mishka is going crazy-and not in a good or funny way! my mom wanted me to keep a kitty because it was going down to 18 one night and he was afraid to come into her house, so she thought, oh i'll take him over to erika's.....well, mishka mina and leo have all been traumatized not to mention joe, the cat that we brought over. mishka sneeked into my room where he was and immediatly attacked him. well, we got that solved by separating them, then she saw leo, her brother, and went after him viciously and cornored him under the bed. ever heard a cat fight under the bed? well, it's not fun!! she darted out and went after him again when we tried to lock her up by herself. then she went after mina when she saw her. mina is my 4 month old and mish treats her like it's her kitten! well, that was on saturday, it is now thursday and joe has been back at my mom's since tuesday. mish and mina have been around eachother for the last couple nights, but she has turned on her 3 times now. leo and mishka got together for the fiirst time again last night and everyone slept together with no problems. well, this morning i left mishka alone because i don't want to leave them together unsupervised. when i got home, i reintroduced them and everything was fine for a while. when my boyfriend got home and we were sitting down to eat, she attacked leo again and then went after mina! this has happend too many times for comfort. my boyfriend tells me that i'll have to either get rid of her or my other furbabies if this doesn't improve, but if i took her to the pound then i'm sure they would put her down because she can't be trusted. does anyone have any idea how to help? i just want my little angels to be ok with one another again. joe's smell is slowly disappearing, but i know it will take time. should i keep them separate until then? any advice would be greatly appreciated.
thanx
erika leo mina and mishka-the evil one

Joe's smell? Did he spray? Better find the source and clean it quickly.
So, I understand from your other post that Mishka, Leo and Mina are siblings? If so, then it sounds like she's telling them who is boss and she's upset from Joe's visit. Don't give up on her!

Even siblings need to be re-introduced gradually. I would separate them and try it again in a few days, and also read this article about how to introduce cats- I hope it helps you

http://www.thecatsite.com/content/view/11/26/

well, i've been introducing them to eachother through a door and then letting them be together sometimes. they have all slept together a few times and then leo and mishka have been together without mina so everything's going good. we got mishka spayed yesterday, so we're hoping that'll calm her down a little bit. she's in the other room right now, still groggy from the drugs. leo's watching her and mina's locked up because she tries to nurse....thanks for the replies. anyway, we'll keep ya'll updated
erika