Invoice items are matched on the description, and optionally status and invoicee all being identicalif specified.
QuantityIf the invoicee is not set to "ignore" it must also match. For type = "Amount", "Percent of Charges" and "Percent of Price" the quantity, price and vat values are updated on all matched invoice items. For the type = "Change Invoicee", only the invoicee is updated on matched items, the quantity, price and vat are unchanged.