I find that I can do 3 hatches together in one large brooder without the oldest excessively bugging the babies, then I start a second brooder. But these are all my own flock in parentage so I don't know how gentle they are compared to other breeds. There is a tiny bit of pecking at the babies, but within an hour they all seem like old friends.
If I had the room I'd stick to two hatches to a brooder.
If I had the room I'd stick to two hatches to a brooder.