FA has a separate calendar (which means it is not changed if the current company fiscal years are modified in any way). The FA calendar gets created based on the current existing company calendar, but after that, it is no longer depended to the company calendar.
If you need to recreate the FA calendar based on an old company calendar configuration, one way to do it is:
1. Make a backup of the company and make sure no one will be doing transactions
2. delete the SY40100 and SY40101, then recreate the old configuration.
3. rebuild the FA calendar
4. delete the sy40100 and 101 again, and restore those tables from the backup or recreate the company years again.. *although it may be a challenge on this part if the company has several years already ...
another thing to consider.. if you have historical plugged in amounts.. after recreating the company fiscal periods, you will be asked to run reconcile the years to recalculate summary info of detailed transactions..
*yeah.. a lot of work...
you may want to do the process in a test server first or something...