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Is mom still with them? Have they been within sight and sound of the main flock? If so, just let them out.
If not, you will need to have a very large area where they can be fenced in with the main flock so they can all see each other for at least a week before they are let out to intermingle. Good luck.

Mom would have done this for you by permitting her to do the natural thing and raise her brood within the flock.How do I integrate them with the other hens?
Is mom still with them? Have they been within sight and sound of the main flock? If so, just let them out.
If not, you will need to have a very large area where they can be fenced in with the main flock so they can all see each other for at least a week before they are let out to intermingle. Good luck.