They are siblings, and like most nest-mates one is noticably smaller than the other. I put them in with peewee#3 who immediately showed them who was boss by standing on them when the food arrived. The new ones don't know it's food yet, but that didn't stop #3 from pushing them around. I hope his sqwarking and begging will encourage them to do the same.
#3 is ready to graduate to Big Aviary, and I've made arrangements to have him transferred this week. #4 and #5 are still a week or two off attempting to fly. #4 has the leaping and flapping right, it's just the horizontal movement side of things he hasn't sorted out. #5 is at least a week off even trying, although that didn't stop him leaping from his nest.
The new birds are doing the "You're not my mum" thing, but I expect the older bird will teach them "Not-mum brings food" and "It's all MINE!"
They are all in the big cage and have already sorted out their perching rights.