Junibutt, how big is the brooder that the Brahma chicks are in? They need as much room as you can give them and they need something else to do to keep from picking on each other. I do not like to separate chicks unless I absolutely have to...it makes it harder to put them back together again. I'd cover any bloody spot with a drop of Blu-kote and put that chick back with the others. Make sure it has some cover...a pile of dry branches or a roost to get up on. Then give them something else to do...make sure they have some grit then give greens/lettuce to pick at, add a dust bath or dishpan full of dry leaves. Or if the weather is good get them outside on the ground for a while each day in a small pen. Think about broody hen raised chicks...they are following her around all day, scratching, eating, learning...they are too busy to spend a lot of time picking on each other.
I would put the Legbars and Brahmas together but I have some large brooder pens to do that in. If they have enough space and cover at your place try it, but keep an eye on them in case of any bullying.
Good luck....let us know how it goes.