I am sort of having the same issue. But in my case my prev. cat wants to play and it scares the feral/semiferal cat and they end up in a fight.
the old cat probably veiws the feral cat as an intruder to her territory. try to do the whole recommended introduction thing the humane society says...
I'm sure this question has been asked before.
But...
I recently took in a stray kitten, perhaps 8-12 months old. He is semi-feral I guess. It took him a long time to warm up to us, like a few months, before we could pick him up and bring him in the house. We got him neutered. He really...