Hi LSS
Using 'transfer of global settings' option within transaction RSA1 in APO, you can import Factory calendars from R3 to APO. Go to RSA1 choose Source systems tab on the left Right click on connected your R3 system there is an option that is "import global settings" Remember all the calendars in APO will be deleted and overwritten. So you need to have a sturdy process in place if you do this so that you dont undo any maintenance done on the APO system independent of R3.
Thank you,
Satish Waghmare