It would allow debit and credit adjustments to be applied against a bill from the same customer but with a different location selected for the bill and the given adjustment, using the prepare payments screen.
Ideally this could be a toggle-able checkbox that depending on the value would group documents by the customer or the customer and location.
It is strange you have the option when manually adding the adjustments on the Checks and Payments screen to add one from a different location but cannot do the same from the process screen. The differing functionality is confusing.
Many users use locations to mark separate warehouse for their customers. The billing department maybe the same for all the different locations leading to adjustment that cannot be applied to the bill.