Is the choir (blue robes) singing any time next week at ND?
The choir usually sings at the Sunday 10:00 a.m. mass (Gregorian). As far as I know there are no special "performances" planned.
Also, at least in American Catholic churches, the color of the choir robes sometimes has to do with the Church season (Lent, Eastertide, etc.) or the specific mass (feast day, etc.). That is, of course, if the church has a collection of different colored robes. Not many that I know of have more than two color options.
Just fyi.