People of different ages who share the same birthday
I'd like to find a word to encompass multiple people who share the same birthday (but were not necessarily born in the same year):
Best wishes to my <birthday-sharing friends> for a wonderful day.
Solution 1:
Birthday twins
I have no citation, but have often heard this used to describe exactly what is asked: two or more, not necessarily related, born on the same day, regardless of year born. Other forms of the same construction are "astro twins," "astrology twins," and "star twins."