It's tempting to put different sized birds in the same cage, but it's not a good idea. Many parrots are aggressive, and don't like other parrots. At one point I had 17 birds -- finches, parakeets and parrots. The finches all lived together in a large aviary. The parakeets lived together in large cages. Each parrot had its own cage. The birds were all let out at the same time. My Meyer's parrot had always gotten along well with all of the smaller birds. But that changed during his first breeding season -- he bit off toes of two of my smaller birds. I had to keep him away from all of the other birds, because he was aggressive.
