I did Magic Music Days with band in high school, except we were there during February.
I’m pretty sure that band is completely different than chorus. We were allowed to select our performance (could do workshops, concert performance, etc.), and we chose to march in the pre-parade. So our experience included a bit of time backstage where we changed and warmed up. I’m assuming that your daughter’s choral group will not march in a parade. I tend to see the choral groups in Tomorrowland… perhaps that’s where they’ll be performing?