Web app "ext. delivery" predefining more quantity than present

You have 18 pieces in stock for an item.

You have an external delivery for the item, on two different line in Bill of material, for 18 + 18 pieces.

The web app predefines 18 for both, even if you do not have them in stock

So when you are trying to move them, you get an error:

You need to manually delete the predefined quantity. The web app should predefine only once, for stock available, like “Pick and Pack” of SAP.