Hi, I took in a stray cat several months ago and she is the friendliest, most affectionate cat I've ever met. She's also very clingy and is literally by my side all the time when I'm home and she's very nervous....of sounds, birds, even cat toys! She's around 5 years old.
I have now taken in another female cat who is around 1.5 years old and I've been keeping her in a separate room and doing some gradual introductions. The cats have been introduced through a small door opening and through a glass door. I've tried feeding them and giving them treats at the same time, on either side of these door, speaking in a calm voice etc. I've also been swapping their rooms around so they can get used to each others' smell and I have 2 Feliway plugins. The new cat is extremely shy and nervous but affectionate and she seems pretty unfazed by my original cat. My original cat, however, is not having any of it. She's hissing and howling, fur all puffed up, won't eat her food/treats if she can see the new cat.
Does anyone have other suggestions I can try? It's only been a few weeks, but I would like to help the process along as much as possible. Does anyone have cats that have never reached a stage where they can be left together?