They were all in one community with the interconnecting doors open so they had access to all three cages. There was something like 20 of them, if I remember correctly, so it was a noisy place and sometimes stressful for the chimps as I would periodically see them chasing each other through the cages screaming.
Yes, 20 sounds about right. The founding females Fifi (1947), Susie (1948), Bessie (1950), Biddy (1950), Lulu (1952) and Mary (1956) all had several offspring each but many died or were exported so there was never more than around 20 in the community at any one time. With so many chimpanzee in such a confined space, it must have been chaos. Infant mortality decreased significantly following the move to the open air exhibit in 1980.