To convert a column of dates to Hebrew dates in Excel, follow these steps:

1. Enable the Hebrew calendar in Excel by going to File Options Advanced Scroll down to "When calculating this workbook" Check the box next to "Use the 1900 date system" Select "Hebrew" from the "Calendar type" dropdown menu.
2. Use the following formula to convert the dates in your column to Hebrew dates:
   
   
   Formula:

   =TEXT(GREGORIAN_TO_HEBREW(A1),"dd/mm/yyyy") 

   In this formula, A1 is the cell reference for the date you want to convert. You can drag this formula down to apply it to the entire column.
3. This formula will convert the Gregorian date in cell A1 to the corresponding Hebrew date in the format of "dd/mm/yyyy". You can then copy and paste this formula to the entire column of dates.
4. Export the column to Word for letters to relatives each year for yahrzeit reminders.