FY20 date pattern starts 30/3/20 but we want to change the date patterns so that this year ends 26/9

Our Current FY20 starts 30/3/20 but we want this to be a short year, ending on 26/9/2020 and the new year starting 27/9/2020.

We tried ending P9 , 10, 11, 12 on 26/9/20 and starting a new year 27/9/2020 but obviously both these years are allocated FY20 as the end of period 1 for both ends in 2020.

How do we best achieve this date change?

Is the only way to do the following:

• Set up a new date pattern for the current year that starts 27/9/2020 to 26/09/2021, and all prior years that had postings.
• Backup F0911 and F0902
• Change company to new date pattern
• Run R099103 recalc ube to update new periods/FY’s in F0911 over all years