Reverse in Received invoices
In an open received invoice, clicking on the Wizards button gives you the option to reverse an existing received document.
The process is very simple and only consists of one pop-up window with the following message: Are you sure you want to reverse the document?
Confirming the choice with the 
option will duplicate the document and quantities will revert to a negative. All other data will remain the same as in the received document. Also, stock in the selected warehouse will decrease. You can also change the data. If you want to reverse only some lines on a document with several lines, the 
(Delete) button will prevent lines from being reversed.
The original document can be seen in the Connected tab. Clicking on the document number will open it.