I am trying to enter credit notes from my supplier for items I returned.
Each credit note has items from more than one previous purchase so I will need to refer to more than one purchase order for each of the credit notes.
How does one go about entering a credit note?
@smokinjo Based on what I have understood from your post, I believe is that what you are looking for is Return / Debit Note and not Return / Credit Note since you are the Customer and not the Supplier.
Regarding your problem, I don’t think that it is possible to reference multiple Purchase Invoice, so you have to create a Return per invoice.