Female kitten moved right on in...

Question:
Hi Everyone....Boy do I have a problem and I hope there is someone out there who has experience with it. Two weeks ago a 4-6 month old female siamese kitten took up residence on the front porch. It was very cold outside and she curled up on a blanket I placed there for her. The next morning there was another cat curled up with her. It could be her brother as they both had the same kind of flea collar. They had been outside for many days as she was especially hungry. She never left, the male goes and comes back. Then on a very cold night I couldn't stand knowing she was out there so I brought her inside. A few days later I took her to my vet (I have three other cats) to get her shots, defleaed, dewormed, and spayed. She lives inside while she heals. The problem: my adult neutered males are very tense due to the baby's desire to romp and play. She unknowingly generates fear of attack by her to the others. Only one cat, Andy, has made an attempt to be near her. He preened her head for a moment. My eldest is the problem. He growls and hisses so much that it incites a riot...the kitten pounces on his back and gets extremely aggressive. This morning all I could see was a ball of rolling colored fur (she's white of course, he's jet black. He, Albert, is 13 years old and may not have the patience to undertake accepting her. I don't want to return her to her owner(s) if I ever find them because they will just neglect her again. The only hope in my opinion is to keep her and hope for the best. Has anyone experienced anything similar? Maybe she's was outside too long AND misses her sibling. I know she'll just come back (maybe I hope she'll come back) if I let her out, and by golly I don't let my cats out at night. While there is always hope, help is needed as well. Oh...Little Mia is quarantined when we are not at home.
Answer:
I would keep her seperated from your other cats some cats take longer to adjust to new family members Cats are very set in their ways and don't like change very well it took one of my cats several months to except my 2 newer cats what i would do is take a blanket that the kitten sleeps on and leave it were your other cats can smell it and vice versa let them get used to her smell i realize they have already seen her but with cats you need to take things slowly give it time things will eventually settle down
Answer:
Thanks for the reply. We went out yesterday to get a large crate big enough for a 25lb doggy. She went crazy over this so we decided to keep her in the family room where we can be with her and separate her at the same time. She's such a love girl! At least now the boys have an opportunity to sniff under the door to get used to her. In fact, Billy and she were playing tug of war with a string under the door. It was very cute. So, I realize that I introduced her way too quickly so I think, as you say, things will settle down given enough time. Thanks, Mark