After 3 months away (even 3 days) she will be treated as an outsider and attacked NFD. She needs to be kept separate but in full view of the others for two weeks before re-introducing her, even during the day.
Sounds as though your coop might be too small. They need a minimum of one square foot per bird in the coop with 9" of perch each and two square metres per bird in a run. As Jaykay said, the fresh quills will be too much of a temptation anyway.