Slowly! and with lots positive reinforcement for sitting side by side without fighting, before they are let loose with the flock. They "KNOW" what I want and what is expected of them, but they are birds and have instincts.... A stern voice or a shout "Knock it off" is all that is required from me to split them apart if they do bicker, that tends to be pretty rare.... they play a lot, they talk a lot, and they have an amazing amount of fun together... and when they are perching and relaxing they tend to all stay in their respective pairs and sometimes in separate areas.... They were all socialized with other birds when they were young, so it is actually pretty easy with my guys. It really depends on the birds... Zero one of my B/G's thinks he is King of the Flock and will sometimes "flex his wings" and drive the others away from a toy or feeding station.... It's kinda funny to watch because zero is smaller than the other guys... and they all have deferred to him!! LOL You need to set up multiple feeding and water stations. Dealing with a flock of birds is much different than dealing with 1 or 2 birds, they have a different mentality.....
My Hyacinth Mason can get highly protective of his GW "mate" Sophie. I can not leave him unattended with the other birds... he could kill the rest of the flock. I usually put them in a separate Aviary to err on the side of caution.
You want to use 1/2 x 1 wire... I think a greenhouse could kill them with the heat....