I've got a red corris, Lepoard, carpenters flasher and another that I can't remember the name of (has a yellow triangle behind his head) all in my 400. They were added in a different times and they have never bothered each other or any other fish.
I have also had 6 lines before in different tanks and they never bothered anything. I have seen 6 lines in the wild while snorkling off the coast of Pago Pago. There were a ton of them swimming in and out of the coral heads. Looked really cool.