I agree with Moosmom. I think supervised meetings would be good. If Ally get's scared and hides, just let Conner get a feel for his new home while she's in hiding. It'll get her used to the fact there's a new kitty in her life.

It'll take a while as its usually on the resident's cat's terms.

sqwelch,
In my opinion, a male kitten would be an easier introduction. You can keep him in your bathroom when Bonnie is overly annoyed...and when she needs some extra attention.