Can I create a debit memo with a positive amount (Payables)?

The definition that our customer manage of debit memo is that it's a document that must increase the debt from an invoice. So, according to that definition, debit memos should have a positive amount in Payables, so they provide a value in favor to the debt.

However, according to oracle support, debit memos can't be created with positive amounts. Is there a way to modify that definition?