Our current arrangement.

With 9 cats in an apartment of 3 rooms in which you're not suppose to have pets to begin with (shhhhh....) So how does it work?

There's the master bedroom, the medium room, the small room and the living room.

The seniors had always been in the master bedroom because they have their own toilet (for bathing and cleaning litter materials which are flushable) and because the window is away from neighbors... on that side of the house is the staircase (we're on the 10th floor and the elevator is much preferred by most if not all), so we only have a neighbor on the other side.

SUNSHINE joined them when she first came in, they got in occasional cat fight but not so bad until she was in her later stage of pregnancy, she was just stressed out and tend to pick on the others more often. So while she was pregnant and until the kittens came, she was placed in the small room (which has a window next to the neighbor). The problem with her being in that room was that she meowed soooo loud that it worried me of complaints that I might get.. she got used to it, but meowed the moment I reach home from work, hence by night time I let her out to roam in the living room.. She had been smart enough to meow at the door if she needed to go in the room. She also had another huge behavioral problem, in which she somehow dislike the litter box, she is trained but somehow she didn't go IN the box but NEXT to box. That was eventually resolved by using clumping litter (more on that in another post).... So because she is the only one using clumping litter, she gets to stay in the living room.

The medium bedroom is off limits, because the window faces the corridor and they just like to peek through the window looking at people passing by.... Now I do not want them to be kicked out, so I better keep them away from that window.
So for a while, it was 4 seniors in the master bedroom, 4 kittens in the small room and SUNSHINE in the living room (luckily she's not a big trouble maker), but that means 3 areas to clean every single day of my life then.

Eventually, the kittens learned about the world outside of their room and also learned to use their ability to meow loudly (they actually formed a choir), and insist on some freedom. I couldn't just let them roam in the living room, for kittens their size they might get lost in between my stuff, and I can't just let them meow like that because I don't want to get any complaints... So, I introduced them to the seniors, (hence BULAN lost his voice, and later BINTANG followed after), but by now they're all getting along well =). So now, I have a total of 8 cats in the master bedroom, with SUNSHINE in the living room. She gets into her cycle of heat now and then, and hence is a bit moody at times and it has been more difficulty for her to get along with the others, I hope all that will improve after she's spayed.

With the current arrangement, another issue arise. I have a kitten who refuse to eat kittens' kibbles and go for adult's kibbles and I have adults who refuse adult's kibbles and eat kittens' kibbles. Now I don't want to have a malnourished kitten with obese adults... so some adjustments will take place... I shall update on that when it happens, soon, I hope.

Their morning routine, looking at birds.

The newcomers happily picked their choice of toys and spots.

SUNNY with the cables.

BELLA with the tunnel.

MJ with the cat spa.

Donna with the rack.

While the seniors took time to adjust..

The princesses looked from above.
BINTANG kept her distance

.... and stared from afar..
YUMIEKO too, kept her distance..
..stared from above...
and later, her expression turned a bit more friendly.
BULAN often joined BINTANG, as she's good with finding good spots..
He could still play, as long as the kittens didn't interupt him..
MICHIKO initially stared a bit...
He wanted to join in their play...
and made little effort to keep his distance.