New Cat Not Getting Along w/ Others :(

On February 4th, we brought home a beautiful 6-year-old Seal Point Siamese from one of our local animal shelters. We named her Kaiya (Kaiya Sky is her full name). Anyways, she's a lovely, gentle creature, but turns into a growling, angry cat whenever our two other cats, Nellie, age 5, a Lynx Point Siamese, and Reggie, age 3, a "tuxedo" go near her. We've found that she despises other cats, and is extremely frightened of them. When we brought her home, we confined her to a room upstairs as is the custom for bringing home a new feline friend. But I must admit that when we brought her home we did not go through the introduction process properly. We brought her home that Wednesday evening and preceded to let her travel downstairs the next morning, running into Reggie. She and Reggie got into a kitty brawl then and have a few times since we have brought her home. Sigh. Reggie, our fun-loving tuxedo wants to "play" with Kaiya and Kaiya wants nothing to do with him whatsoever, hence the fight. This began her aggression towards Reggie and Nellie, understandably. I know this mistake that we, her family made is going to be hard to unravel and make right.
Anyways, Kaiya now stays to the room we presented her with when she first came home. She uses her paws and claws to open up the cupboards in the room. She stays in the dark cupboards all day long because of her fear and mostly only comes out at meal times. :( She is such a loving cat to humans, albeit disliking our other felines. She is always "alert" for them and can't settle down. We've tried bringing her downstairs a few times and just placed her on the couch, but she is so stiff, unsettled, and uncomfortable. Within a few minutes, she's flying up the stairs back into "her room" again and into the cupboards. What can we do to help her at least tolerate Nellie and Reggie? Will she ever bloom again into the wonderful kitty we fell in the love with at the start? While she does have her loving moments towards us, and I've had a few select purr sessions with her in which she rubs my hands and legs so lovingly, she feels restrained because she is so stressed out with Nellie and Reggie. I'd really appreciate any input you have and advice you may give. I am just so sad right now because I don't want to see this precious girl live in fear and stress. It has almost been a month since we brought her home, and she just can't tolerate Nellie and Reggie. Thank you all so very much.
:(

My suggestions would be to close her in the room like you did in the beginning and not let the cats interact. Spend plenty of time with the new cat until she's comfortable comming out of the cupboards and is acting more like the cat you fell in love with.

Once that finally happens (it may take days or weeks), then start the introduction process over again properly. Use the Feliway plug in's to help minimize stress.

Try also taking a cloth and wiping it over the old cats then wiping it on the new cat, and back again, so they can get each other's smells on them. If that goes well try feeding the new cat right at the door so she can smell the other cats but know it's ok and they can't hurt her.

Once she's ok with that, shut in the two old cats in a room, and leave the door open to the new cat's room. Let her come out when she wants to, don't force it. If after a few hours she doesn't try to come out, shut the door, let out the other cats and try again the next day.

If she does come out, let her explore at her own pace and get her smells around the house for the other kitties to smell.

If that starts going ok, then you can try SHORT supervised introductions face to face. There are several ways to do that, one is to let one old kitty at a time into the new kitty's room, OR put an old kitty in a carrier and set it in the new kitty's room for a short time gradually increasing the time if things are going well. This would show the new kitty that she doesn't have to fear the old kitty's, at least on her turf (her room).

I've used both ways depending on the cat. In my case, starting from scratch that way, it sometimes took up to 2 months to make proper introductions, and at that I still have some cats that just will not get along no matter what. There are no guarantees, however these steps (and more that other people can add) should give you the best chance of having the cats at least tolerate each other.

Good luck.

Thank you, Catlady711, for your help! We will indeed start the introduction process again, and use your suggestions above. They are very helpful. We do appreciate them very much! What beautiful felines you have. :D:love: Attached is a picture of Kaiya, our newest addition whom this thread is all about! :love: Thank you. ~Catloverforever~
P.S. To any one else who has suggestions on this matter, please don't hesitate to put your two cents in. They'd be much appreciated.