We set up the spare bedroom as Moray's "den." That had his litter box and food and water and some toys and a scratching post, all for him.
However, we did allow him to explore straight away under our supervision.
Tinks really didnt like it. He was used to having his big ginger Ross around, and suddenly Ross wasnt there, and then Moray was (we lost Ross to an RTA)
Tinks showed his confusion and unhappiness by scooting off every time he saw Moray, so we began to confine Moray to his room, and give Tinks the run of the house, with only small periods of supervised "contact".
The thing is, Moray was great - he's a very gentle and intuitive cat, wise beyond his not-quite-a-year-yet, and he knew he had to take things very gently with this new friend and in his new home (treading on eggshells as we all were.)
And Tinks has such a big heart and a generous disposition that it wasnt long before he became curious about the play sounds that emanated from the spare bedroom during Moray's "den" times, and he''d sit outside and listen.
It wasnt long after that we were able to introduce the joint play sessions and the joint feeding, and in a total of two to three weeks, Moray had managed to work his way into all our hearts and get close enough to Tinks to actiually - touch - him.
The only way you'll really be able to tell how it will you for you, Bruno and Bebe is to try it out - your flat is small, so you have to work with what you have, but it should be eminently do-able, so long as you dont try to hurry the process and let the cats set the pace.
I think the cat play pen will be a useful tool in that regard.
