@tut, thank you,
I know that a credit note affects the item in inventory sales and on-hand, but I may not issue it antedated and the adjustment should reflect in Balance and P&L 2020.
It’s just an accounting adjustment of revenue recognition not recorded in a specific period.
The use of a secondary sales account is not the right option, since it will not affect the Inventory Profit Margin.
A similar issue was raised by Brucanna a few years ago in the thread 6234, but probably there was no sequel.