So long Dory, we hardly knew ye

Dory, our resident squirrel, hellraiser and B.B.-baiter, is off to a (hopefully) happier home.
God knows this one didn't work out.
Streak was mostly neutral on Dory. She'd hiss and growl only if the kitten approached her wanting to play, but would avoid her the rest of the time. B.B, on the other hand, actively stalked her, no fooling around. At least once a day (or more likely, once a night) we'd be treated to the aural spectacle of two cats having a melee. Imagine, in your mind's ear, a 78 rpm recording of ten kittens being stepped on, played at 33 1/2. That's been our house for the last little while.
At the very first, B.B reacted very badly to the new kitten. After a couple of days, though, you could see her trying to make friends. Unfortunately, she'd made a piss-poor first impression and Dory was having none of it. So B.B. figured 'okay, this cat hates me, I can hate it too'. Cue the yowling hissyfits.
For some reason, it mortally offended B.B. to see Dory using a litterbox. B.B and Streak have shared a box forever; we bought a new one for the kitten, but it made no difference. B.B would try to pounce on Dory while she attended to business, and that didn't go over well, either.
We held out for three weeks, hoping that things would get better. They didn't. So now Dory's off to a new house with a mother and daughter...and no other cats. I think she'll be much happier.
Kind of attached to this cat after only a month...this is why we can't be foster parents. If it's this bad with a kitten after four weeks, how bad would it be when our foster child finds her 'forever family' after four years? We're more the 'forever family' type...