A lot depends on the size of your brooder. Space and how the space is set up is crucial to chicken behavior.
How much space do you have? Pictures really help us help you. Thing is you have almost doubled your flock. What was enough space for tiny chicks will rapidly become not enough space for growing birds, and the more chicks you add the faster that happens.
If you are ready to move the flock out to a coop/run. I would try it, and try it soon. See what happens. Interfere if necessary. Putting them together in a strange place generally helps. The new space should have a lot of clutter, things to get under, things to get on top of, little walls where a bird can step out of sight.
There should be multiple feed bowls - set up so that while eating at one, a bird can't see a bird eating at another. I would have 4-5 bowls set up. Keeps it harder to defend.
You might get a mean older chick, that is very aggressive (might be a rooster) pull that bird if the rest of them are getting along. Put him/her back in the brooder for a few days, so the rest of the group can figure things out.
Mrs K