You can certainly try, but do it under close supervision, and the earlier the better. At some point she will stop and think "This is my family" and if you try to add more she might be quite aggressive to them.
I'd dump them all in at once and see how she reacts. If she doesn't seem worried, and she doesn't peck at them - all good. But if you notice she looks upset by it - getting vocal, pacing, pecking - get them out quick. It doesn't take long for things to go bad, so be ready to whip them out if needs be.
If you get all of the chicks under/near her, and she still looks calm after an hour, I'd say you're safe. But I really would do them all at once, because at some point she will think new chicks are strangers and not hers.
Good luck! I'm keen to see how it goes.
Krista x