Occasions and events
Occasions are the kinds of days; events are each person’s actual dates.
An occasion is a kind of day — Birthday, Work anniversary, Graduation, or anything you create under Occasions. An event is one person's actual date for it. Set events on a member's page, or collect them automatically through a join link that asks for the date.
Recurring events (like birthdays) re-arm every year after the celebration — set once, celebrate forever.