Hi, I know others here will disagree with me, but having lived through it soo many times, I have to say that I think your best bet is figuring out how to separate them ... for good, not just for intro. time. The younger cats will inevitably (the male esp.) start going after the older cat to assert domination (it's what they do, every darn time, eventually) and she won't be able to defend herself once he's grown, but there's no way to 'change his mind' as it's a very hard wired 'instinct'. If there's any way, starting right now, to get your cat used to spending time in whatever room you feel is appropriate (with her own box, water, feeding station, and pillows) and make a point of playing with her there, plus keeping the door closed for extended times, she may adapt very quickly. When the new cats are settled in, and the regular intro. procedures for all are done with you being there to supervise (every time), make sure she knows where her safe place is (and of course don't let the male in there if she's around). In other words, she shouldn't be alone with him as she gets older, because I'm afraid the male will go after her and at best make her miserable, at worst real damage could be done, even if the behaviour doesn't start for some time, even a year or so.