Introducing a young cat into a household with two 10yr old cats

Question
Hi,
My sister has recently split with her partner and moved in with me.  I have two short hair tabby's, brother and sister, and 10 years old.  My sister has a tabby not even 1 year old, who is very timid around strangers.  Her tabby is currently still at her old address (alone, but cared for) and she wants to move him in with us.
My sister's cat was brought up by a breader who had a house full of cats so I do not think it will be a problem for him to adopt to the new living conditions (i.e. other cats), but I am concerned for my two not accepting him.  Can you give me any advice or tips on how to best approach this which will cause them the least stress and enable them to co-habit well together?
Much appreciated
Clair

Answer
Hi Clair,

It's nice of you to let your sister and her kitty come live with you, and a good idea to think ahead! Here is an article I wrote on introducing a new cat to resident cats. With older cats (10 is not old, but old enough to have decided they know how things "should" be in their home) it's important to take things pretty slowly.

Usually if the new cat is very easy going as your sister's cat sounds, there are fewer problems because he won't challenge the authority of your cats.

http://catnet.stanford.edu/articles/introducing_cats.html

Rubbing a towel or washcloth on your cats' cheeks and then rubbing that "scented" towel all over your sister's cat before their first meeting will make him smell familiar and help ease the introduction as well.

Good luck for a harmonious home!