Truly enjoyed reading through your trip report thus far.
I have a friend (DVC owners) whose high school aged daughter sang at Epcot in the CP. Did you know high school choirs are invited to perform there with the Disney cast member singers (including VoL singers)? They don’t really advertise or announce that there are high school choirs joining in. My friend’s daughter was over the moon about singing there as they are clearly huge Disney fans (being DVC members). They performed on a night John Stamos was narrating. So it may have been when you were there.
Thanks once more for the great trip log and fantastic photos!