You can deactivate and activate for an account for her.
I think that will be better as you can then limit what books are on her account i.e. if you share accounts then EVERY new book you get will be available to her until you remove it.
If you want to read something like Shades of Grey or something that might have some adult situations or too much violence.
Then having a completely separate account for your daughter makes sense.
Yes, what 5ivedom suggested. Plus, if you archive the unwanted books from the N1E, then they will archive from your NC when you do a sync. You can't archive from just one device when multiple devices are on one account.