To be honest Kay, I think you are being a bit posh eek: Nice house, nice cats and one that is not quite fitting in. If it were me I'd have the cat flap sealed so you have control over who goes in and out, also that you dont lose any. I have took in an adult rescue cat and she has fitted in just fine with my Persians and they all stay inside together and get on just fine. I wouldnt consider parting with her personally, give her a better chance!