From a reader:
Please don’t think I’m a heretic, but I was at one of those great
circumstances where multiple celebrants sang the last part of the
Eucharistic prayer (which I think is the doxology). They sang it
together and on key. That is so wonderful.
I would love to have a musical setting where it would be possible for
a cantor, choir, or congregation to harmonize with the celebrant(s). I understand it would confuse roles to have non-priests sing any of the same words as the priests. How would I explore this?
You don’t explore it. It is forbidden for anyone other than the celebrant and, if present, concelebrants to sing that part at the end of the Eucharistic Prayer(s). Even priests or bishops who are present, but not concelebrating, cannot sing that together with the celebrant.