Firstly, I've been a little on edge over the new chicks and whether they would be OK. There wasn't any obvious nastiness. We did see a bit of pecking, and I was concerned that the teenytinies might accidentally get injured, and then if blood was drawn there might be a frenzy. (Remember Hannibal the Cannibal?)
The teenytinies did end up spending a fair bit of time in their sectioned off area. We removed the lid as was concerned it was getting too hot, and we removed the cardboard from the entrance. I think they were just exhausted with all the change and, also, teenytinies do tend to sleep a lot.
I put in a third feeding and watering station, just in case.
I installed a baby monitor so that I could hear if there was any trouble. I also popped in frequently. For the first 24 hours, the newbies slept a lot, or were together-ish, slightly separate from the others. When they were awake, they were mixed in.
Then I went in and found all the chicks sleeping in 2 piles, with a mix of chicks in each pile. Since then I find them all over the place, and there doesn't seem to be any trouble. The teenytinies do still sometimes pop under the hen in their safe area, but usually they are wandering around the brooder, or are sitting under the other (higher) hen with some of the others.
They are so tiny and so fast! The Araucanas look like penguin chicks.
I waited until last night to pick the newbies up for the first time. I wanted them to get over the stress of the move and being put in with a load of strangers first.
If the weather is hot tomorrow, then they'll all be going out together for a while. I've bought another electric hen to use outside, because it's such a faff undoing some of the shed ones and setting it up outside, then bringing it back in. I hope it arrives tomorrow.