Hiya,
I've read Wizz's advice and we're following that for now.
I've got some feliway plug-ins.
At the moment she's in the spare room, the door has two skins, one solid wood and the other is a cage door, as we used to keep the foster cats in there.
The solid door is open but the cage door shut, so they can see eachother but they can't get to one another.
They've been in the cattery together this weekend, although in pens next to one another, not the same one.
The new cat wants to play with our resident cat, but unfortunately the feeling's not mutual