Family Historian User Group

How would you deal with multiple dates for the same fact (not necessarily different dates, but in different calendars)? There's no right answer, but I would appreciate your input.
I have a large Jewish branch originating in the Baltic countries, and I must juggle between the Georgian, Julian and Hebrew calendars in their records:
The official system up until 1916 was the Julian one. Then it switched to the Georgian, and all prior dates were retroactively converted on official documentation - passports, censuses etc. Meanwhile, vital records additionaly employed the Hebrew calendar (and it was sometimes used exclusively on headstones).
For the sake of accuracy, I recorded dates based on the earliest available source. When optional I stuck with the Julian rather than the Hebrew out of convenience. Thus, most events in this tree prior to 1916 are in the Julian [j] calendar. Unfortunately, FH's age calculator doesn't support this, and adding multiple facts for the same also disables this feature.
Would you keep a mixed tree? Convert all the dates to a single system? Record all three?

One possibility is to use a Date Phrase to record the Julian and/or Hebew date, and in the 'interpreted as' field enter the equivalent Gregorian date.

FH will then be able to use the Gregorian date for age calculations, but the Julian or Hebrew date will be displayed in brackets after the Gregorian date, in reports and diagrams.

For what it's worth, as a simplistic microcosm, even when I go back beyond 1752 (in England & Wales) I do not set the dates to Julian. My reason for that is that setting the calendar for a date to Julian removes the option for dual dating. This is unfortunate as it leads to confusion over whether being born in December 1740 and dying in February 1740 is possible or not. It's also sort-of-incorrect as dual dating was used in the real world prior to 1752. I just leave it to the default Gregorian and record those dates (taken exactly from the contemporary source) as born in December 1740 and dying in February 1740/41.

All you have to remember is that (a) pre-1752 English & Welsh dates are in the Julian calendar, despite my apparently using the Gregorian, and that (b) 18 January (say) in England was not 18 January in France.

Seems to work OK for me.

That might help by removing one option - providing you are consistent and use the contemporary calendar's dates - this may need some de-conversion of pre-1916 events if you only have the converted Gregorian date.... But consistency is probably a good idea anyway.