Sorry if you've already mentioned this, but why is Z still in quarantine after six weeks - is it because he's unable to get along with your other cat? If so, what have you done to integrate them? There have been several threads on this site that has addressed introducing a new cat/pet into the household, and many techniques to consider - hopefully one or more of them will work for you.
Long story - yes, it's because he and my DSH do not egt along. We started off doing the socks rubbed on a kitty's face, then given to the other kitty. I tried moving my DSH's food dish closer and closer to Z's door so they could eat on opposite sides of his door. But his door is across a room and up seven steps. But right after he arrived, he escaped twice and went after her and since then she's (understandably) terrified of him. I could get her food dish to the steps, but she (Rheya) refused to go up them. So that hasn't really worked.
I had tried room swapping a couple of times, but Rheya was very unhappy to be in his room. Marilyn suggested I put Rheya in a different room, just so Z could get out some and that has been OK.
I had also put each cat in a crate, then put them in the same room, though not close. Neither one was very happy. And then one evening, I put the kitties in the crates, sat down on the floor between them, with a toy, and opened the doors. In my mind, the cats would come out cautiously and I could use the toy to distract them from focusing on each other. This was a huge mistake. Rheya was cautious, Z was not, and as before, he went straight for her. Rheya now has very much a "victim" attitude, which is not helping.
So - that happened maybe three weeks ago? I managed to find Marilyn and setup a Skype session with her for this week. In the meantime, we've just been treading water until I can get some guidance from her. I can't wait - Z and I are ready to get him out (Rheya not so much.)
Any and all advice is welcome!