Crediting A/P Reserve Invoices 
Use one of the procedures below to record a credit for A/P reserve invoices, even if you have received some or all of the goods you ordered. This may be necessary if you have already paid the A/P reserve invoice, but received damaged goods, and would now like to be reimbursed for the expenses.
Prerequisites
An A/P reserve invoice exists for the vendor.
Procedure
Copying an A/P Reserve Invoice into an A/P Credit Memo
From the SAP Business One Main Menu, choose
Purchasing – A/P 
A/P Reserve Invoice. 
and open the relevant document.Click the Copy To button and select A/P Credit Memo.
The A/P Credit Memo window appears listing all items that were included in the A/P reserve invoice. If not all the items have been delivered yet, the original item line is divided into two lines – one for delivered items, one for non delivered items. If there are several related goods receipt POs based on one A/P reserve invoice, the items are divided according to the goods receipt PO. The goods receipt PO number is displayed in the A/P credit memo.
Enter the necessary data and choose Add. The A/P credit memo for the A/P reserve invoice is created.
Copying an A/P Credit Memo from an A/P Reserve Invoice
From the SAP Business One Main Menu, choose
Purchasing – A/P A/P Credit Memo .Specify the relevant vendor.
Click the Copy From button and select A/P Invoices.
The List of A/P Invoices window appears.
Select the A/P invoice that you want to credit and click Choose.
In the Draw Document Wizard window, select which exchange rate to use and how to copy the data into the credit memo, and choose Finish.
Enter the necessary data and choose Add.
The A/P credit memo for the A/P reserve invoice is created. If not all the items have been delivered yet, the original item line is divided into two parts – one for delivered items, one for non delivered items. If there are several related goods receipt POs based on one A/P reserve invoice, the items are divided according to the goods receipt PO. The goods receipt PO number is displayed in the A/P credit memo.