Recalculation of Free Goods During Sales Return S/4HANA 1809

I am looking for expert opinion:

Scenario: Sold SKU A 100 pcs(item 10 tan) with Free SKU B 10pcs(item 20 Tann). While min order qty was 10 to be entitled of 1 FG(exclusive)

Now Customer wanted to return only 50Pcs (Ren) with Ref Invoice/Sales Order, but the system still asking for the 10pcs (Renn) of FG, means not considering the changes in mainline item.

I wanted to know is there any standard mechanism by using that we can control it and performed the re-calculation of Free Goods? OR it has to be controlled manually/SOP only.

Please share your valuable input into this based on your past encounter within S/4HANA 1809.

Many thanks in advance for your valuable feedback!