How long since you added them? How old are each set of chickens? Do they have plenty of space to get away from each other? Do you have multiple feeders and waterers so the new ones don't get bullied away from food and water? How about hiding places? Do you have a way for the new ones to get out of the line of vision of the others?How long after adding in new chickens should I expect things to settle and for them to peacefully co-exist? Are there signs that they just simply will not get along ever?
It'll happen eventually. Sometimes two combined flocks end up being just that. Two sub-flocks. Sometimes they'll get along better once the younger ones are laying. Sometimes they get along better after "bonding" all winter in a smaller area. As long as the older ones aren't viciously attacking the younger ones, I wouldn't be too concerned. Another thought would be to separate the couple of bullies for a week or two, to try to reset things.They are 11 months and around 19 weeks. They have a huge chunk of yard, many food/water bowls, and many places to hide. They've been together for about 10 days but a couple of them just keep chasing and pecking. There's been no fights but one of the little ones had a bloody peck spot on her beak this evening