Derived Factor Formula looking at Person's age as of event and as of first of calendar year

Summary:

Requirement: Dependents age off of benefits as such:

Medical: end of the calendar year of 26th birthdate- client has a fiscal year plan year (10/1 - 9/30).

Dental/Vision/Dep Life - coverage ends as of event date of 26th birthdate (dep life) or end of month of 26th birthdate (den/vis)

I currently have configured 2 separate derived factors -

Medical - Persons age as of first of calendar year - Then use a different life event effective beginning of next calendar year to end date medical for those that aged off in the prior year and attach it to those med plans only.