Selected sanctorale solemnities suppressing Advent Sundays in some particular calendars #96
Description
... Such dispensations have already been granted for other just causes such as the celebration of the Immaculate Conception in Spain and Italy and that of Our Lady of Guadalupe in Mexico. These feasts are celebrated even if they coincide with a Sunday of Advent, as the dates are intimately tied up to the religious practice of the people in these countries and are also celebrated as civil holidays.
https://www.ewtn.com/catholicism/library/papal-funeral-continued-4944
Such a custom calendar rule can currently be implemented only by coding a subclass of Calendar with customized precedence logic (although possibly customized Transfers may suffice). Another way would be to assign the sanctorale solemnities in question the highest rank or Ranks::TRIDUUM, but that's very dirty and may have various unexpected consequences.