I called Petsmart about the filaway and she said to spray it where they are marking..... but they are both fixed and are not marking.... so I really wouldn't know what to do with it....

Please tell me how I can use it...

Another question: When you got Jupiter last year, was Tinky also acting like that? And where they on good terms all the time or did they only tolerate each other?
When we got Jupiter it took them about a week and a half before Tinky wouldn't growl at him... but she never hid from him and she didn't scream ..... she would only growl and hiss..

They have never really been the best of friends... they play and wash each other... but they never really cuddle and sleep together or anything...

And too bad for the little kitten! Why does your sister think the house isn't a good place for a kitten?
My sister has a 5 year old daughter and a 6 month old son and her husband has 3 daughters that come over every other weekend..... so I am guessing that she realizes that they may not be mature enough to handle a baby kitten.... I am not really sure though... My sister is pretty strict so.. if she taught them how to handle a kitten .. I KNOW.. they would be good with it.