Q: Can our Jesuit community celebrate St. Peter Faber at Mass on August 2. (He was canonized in 2013).
A: I’m assuming that the rector of a church or the presider of a Mass with the people on August 2 may authorize a Mass for St. Peter Faber in place of the obligatory memorial of St. Alphonsus Liguori if he judges that there is some real necessity or pastoral advantage.
GIRM 376 gives that permission on obligatory memorials in regard to Masses for Various Needs and Occasions and Votive Masses, but it is silent about observing the memorial of some other saint in the martyrology on that day.
On an optional memorial, GIRM 355 c permits the substitution of Masses for Various Needs and Occasions, and Votive Masses, AND and other saints listed in the martyrology on the same day. Since 355c groups those saints in the same category, I’m led to believe that the same could apply to 376. But honestly it doesn’t explicitly say so.