From a priest:
This Sunday is the patronal feast of our parish, Sts Joachim and Ann. We have an extraordinary form Mass every Sunday. Do you know if there is a collect for the extraordinary form that mentions both Joachim and Ann that might licitly be used in the extraordinary form?
The present legislation indicates that the two forms (I think they are rites, but that’s another bowl of chowder) should not be mixed.
It seems to me that the best approach would be, on the Feast of St. Ann, to double your collect and pray also the collect for St. Joachim.