Hi,
This mix may or may not continue to work out. It depends on whether they get territorial. Do not ever give them anything that can be used as a nest – no bird huts, tents, nests, boxes – absolutely nothing they can sit in like it’s a nest. With multiple birds in one cage and especially mixed species, they can start fighting if you let them start breeding. As for the larger cage, you might try starting off with the older bird in it, since this is what happened with the first cage. And once that bird is settled in, introduce the others in the same manner as before. Mainly watch for any chasing or fighting. And there should be multiple sources of food and water so no bird can claim all the food.
Thank you for asking Lafeber,
Brenda