Sounds like you are on the right track.I think one of my near 3 week old Buff Orps has been traumatized by the move to the garage and the introduction of the new chicks.
She was already the paranoid one when ever she was left alone in the box. She has developed a bit of a mean streak as of late. We had to separate her from the chicks but couldn't leave her alone so her more docile companion stayed with her. She apparently tries to bite now and again turning her in to quite the little drama queen. We shall see how she behaves this weekend. We may have to change the heat light for her. I was reading that the red light seems to make them more docil where as the white lite can lead to aggressiveness. I couldn't get a red light in time when we first got them so I picked up a white one and the del's who were older seemed fine with it. I hope to get the bigger brooder box finished this weekend so maybe we can give them all a good mount of space and separate them while still able to see each other. Maybe that will help and they can all get attention at the same time.
Only have 3 weeks now to get the new coop built. (4 if I push it).
It does take time for them to integrate and work out pecking order stuff. The red light will help and the brooder plates make a big difference. Brinsea makes them and Premier1 has a brand too.
They get normal day and night with those since you do not need to leave the light on at night. They also have a nice dark place to go to if they are being picked on.