You should keep the number of edits to the approved invoices to the minimum possible. This is because once a purchase entry is approved, the accounting entries for these are created in the system. Hence when it is edited, the corresponding entries has to be passed into the accounting system and the vendor GL will reflect these.
However, in the event that the purchase has to be amended, you need to manage it carefully. If the change is to the invoice number, date or rate, you can reject the current bill and then create a new bill using the same good receipt. Then you can update the bill with the new invoice and rate. Once the bill is approved the revised purchase price will reflect on the item.
If there are quantity changes, then the bill has to be rejected and the GRN has to be deleted. You can create a new GRN using the cancelled GRN so that you do not have to manually create it again.
Refer the below video for the details.