Support for holidays on a particular Sunday in month rather then date

[mdegat01]

I use this component a lot to give me a heads up about upcoming important days of the year such as family birthdays, anniversaries or holidays I have to prepare for with gifts/planning like Christmas and Valentine's day.

One challenge I have though is there's currently no way to add an entity for days which don't fall on a particular date but rather a particular Sunday in a month. For example in the United States Mother's Day falls on the second Sunday in May and Father's Day falls on the third Sunday in June.

I realize this is kind of a stretch from the original intent of this component (keeping track of anniversaries) but was wondering if it was possible to enhance it to support this use case?

[DrSpaldo]

Agreed, this would be great to remember mothers day :)