Hi Tomek,
In new FI-AA it is no longer possible to define a "Delta Area", as we know it from classical FI-AA. These Delta Areas where usually part of a so called Ledger Scenario, which was how parallel valuation with mutliple ledgers had been realized in FI-AA.
The former Delta Area was necessary to post APC adjustments for the parallel ledger. This is why it was possible to define a derived area that posts to GL and which base areas belong to different ledger groups. It's also why the flag "Derived area as real area" was added to the setup (because otherwise the delta postings could not hit the same accounts as in the base areas, because normally a derived area uses only a limited set of accounts).
In new FI-AA there is for each Ledger Group a depreciation area that posts "realtime". This area posts the complete APC amount and delta postings are no longer necessary. I assume this might be the reason why it is no longer neccessary to define such an area.
For your scenario I can only think of following options:
a) If you want to see the Local GAAP/IFRS difference in FI-AA only, set the flag "area for reporting purposes only". Then the base areas no longer need to belong to the same ledger groups. But such an area may not post to GL.
See documentation of the flag:
"(...) The derived depreciation area that shows the differences in APC between two accounting principles (also called the delta area) is only allowed to be defined as a depreciation area for reporting purposes."
b) If you need the derived area to post, you have to define another area in IFRS ledger for which you ensure it contains same values as area 01. You can then use this area as a base area for your derived area.
Best regards, Michael