This will be a problem as your Favorelle is a breed that is very docile and often picked on by more aggressive breeds. She has to start at the bottom of the pecking order again, a place she may never have left.
First a question. Have you had them in sight of each other through fence line? That needs to happen for several days to a week for the Favorelle.
Babes can usually hold their own as long as they have places to hide and run UNLESS you have overly aggressive birds. 3 weeks can work, 4 is better, with the right flock. It works best if momma is there to protect them from aggressive birds. However, momma Favorelle will be hazed to get back into the flock, which can be a bit tough, so she probably won't do a good job of protecting the babes.
If it is one hen, you may consider putting HER in the small coop and letting the Favorelle and babes integrate with the friendlier birds in the flock. Then when the chicks are at about 6 weeks of age, holding their own and fledged, and the Favorelle re-integrated, let the aggressive alpha hen into the main flock again.
Otherwise, you may have to let the Favorelle and babes be alone in the small coop, with visual, for a bit longer.
My thoughts and experiences.
LofMc