The Case:
- Current Fiscal Year = FY17;
- Some data is brought forwarded from Dec16;

Option 1: Set new Current Fiscal Year + Increase Number of Past Years by 1
Option 1 results:
- Original brought-forward value is still in place;
- Original FY17 data is still in place;
- New FY is added;
- Module size is increased.

Option 2: Adjust Current Fiscal Year settings
Option 2 resuls:
- Original brought-forward value (Dec 16) is lost;
- Original FY17 data is lost;
- New FY is added;
- Module size is same;
- Dec17 value in line item with brought forward flag is equal to Dec17 value before time adjustment.

If you have other ideas on how to move anaplan model to the next FY, please share in comments.
BR,
Igor