So this chick group is all living together in harmony?
But living far away from the 2 older hens?
The 2 groups need to be next to each other for more than a week.
When you let them be together were they free ranging ....or in a run.... or...?
I've
integrated 4 week olds into adult flock but they were living in adjacent housing 24/7 for a few weeks, plus I have
lots of space and the chicks could get to a safe place that the adults could not.
Knowing more about your coops/runs/etc...size of areas in feet by feet and pics would be great...would help us help you with more specific suggestions.
Having a brand new coop and run could ameliorate territoriality issues if you put them all in there at the same time.....still need adequate space, multiple feed/water and hiding places tho.
Integration Basics notes:
It's all about territory and resources(space/food/water).
Existing birds will almost always attack new ones to defend their resources.
Understanding chicken behaviors is essential to integrating new birds into your flock.
Confine new birds within sight but physically segregated from older/existing birds for several weeks, so they can see and get used to each other but not physically interact.
In adjacent runs, spread scratch grains along the dividing mesh, best if mesh is just big enough for birds to stick their head thru, so they get used to eating together.
The more space, the better. Birds will peck to establish dominance, the pecked bird needs space to get away. As long as there's no copious blood drawn and/or new bird is not trapped/pinned down and beaten unmercilessly, let them work it out. Every time you interfere or remove new birds, they'll have to start the pecking order thing all over again.
Multiple feed/water stations. Dominance issues are most often carried out over sustenance, more stations lessens the frequency of that issue.
Places for the new birds to hide 'out of line of sight'(but not a dead end trap) and/or up and away from any bully birds. Roosts, pallets or boards leaned up against walls or up on concrete blocks, old chairs tables, branches, logs, stumps out in the run can
really help. Lots of diversion and places to 'hide' instead of bare wide open run.
This used to be a better search, new format has reduced it's efficacy, but still:
Read up on integration..... BYC advanced search>titles only>
integration
This is good place to start reading, BUT some info is outdated IMO:
http://www.backyardchickens.com/a/adding-to-your-flock