She would probably prefer to take them into the big coop and teach them roosting in there if possible before giving them up entirely, most of our hens take there little ones up onto the roost for a week or two before cutting them loose. But that doesn't mean every hen will do the same.
To help things along you can boot out the rest of the flock during the day but keep mama and chicks in the run. then use treats to encourage them up the ramp into the main coop. just scatter a few treats up along the ramp and try to get the most forward of the chicks to follow them up. Once the chicks go up the ramp a time or two they will get the idea. Once you get the chicks and mama into the coop you can offer them a treat or a feeder with some preferred goodies in it so the little ones are more willing to stay in the coop for a short time, this way they won't view it as much as a 'foreign' place and be more willing to go in with their mama the next time.
If mama tries to get them into the coop again you can assist her in encouraging them up the ramp and then let her do the rest, it may take her a few tries to get them to cooperate though, the little buggers are creatures of habit, so you may find them sleeping in a pile on the floor for a bit, but they will eventually get it. You may end up having to either block off or entirely remove the little coop they have been using though...