I've seen hs choirs perform at Carnation Gardens, usually late morning or early afternoon. I know the hs bands are bused into the DL backstage area behind Toontown where they have dressing rooms to change in to/out of uniforms, and march to either the Small World or Main Street end of the parade route. For a choir performing at Carnation Gardens I suspect they'd walk from the dressing area to the CG backstage area via the tunnel under the old Skyway Fantasyland terminal. Sometimes the MMD program includes a backstage seminar in a studio which would otherwise be used for rehearsals for the DL entertainment folks. That's about all I can offer, maybe someone else has something more definitive.
