Well sorry for not knowing about "common sense" of chooks. I've had no experience with adding new birds and all that with them. My mum's friend breeds chickens, and just came and put them in the pen one day when we weren't home, and while the dominant hen did peck them a little bit, she only did that for a few hours before stopping.
The three of them are fine: they only get pecked when they get in the way of the other chooks. So they are "apart" of the flock, but I was just suprised that the rooster pecked them when one of them jumped up on the roost. I always give them their own little feeder out of the way of the other chooks, and throw another bit of silverbeet in away from all the other leafy scraps, so they actually have a chance to eat.
Obviously I am not going to "chuck" these day old chicks I am getting in with those other ones until they at least 8 weeks old. I am not that stupid.
And the only reason I thought a rooster was a peacekeeper was I thought that someone had described him as one in another thread. Though that might have been about their certain rooster or something. I don't know.
Sorry for coming across as rude, but seriously, they are all fine and dandy. My nan bought down a whopper of a chook the other day, because apparently she goes broody on and off (I think she's a white sussex or something) and we wanted to put some fertilized eggs under her. Because she is so big, she could easily fend for herself and stand up for herself, so she was just bought in how she is. Yes, this may have upset the pecking order, but she never goes causing trouble, and no one has caused her any trouble yet (at first, there was a fight, but they've stopped that now) so it's all good. Only day three of her being in there too.