Like someone said earlier the whole approach of letting them see each other before they flock helps the whole pecking order process.
The pecking order is unavoidable, it's how they figure out who is where in their family. Over the summer I had gotten several donation chickens and had them chill in my chicken tractor for a day so the other chickens could see them without physical contact. You could probably do something very similar if you don't have a chicken tractor, like a coop or even a dog kennel, the important part is that they get to see everyone without physical contact. From my understanding you are knocking out 2 steps to their 3 step pecking order. It also depends what gender and how many you are introducing. 6 pullets shouldn't be that hard :] remember that pecking is normal, it's part of their social system.