This is similar to my issue. I do warranty repair for XYZ company. I also purchase parts from the same company. The twist is I use projects to track the item, and the end user as a sub-customer of XYZ company that will ultimately pay the invoice for the repair. When XYZ pays for the repair, it is done by credit memo. Then, I must balance the books by applying it to the repair invoice and the bill for the parts ordered and purchased through XYZ company.  thus my vender is also a customer. How do I do that?

thank you