Need to Automatically Decrement Inventory

Hi all, hoping to get some ideas from the community. Basically, we had a process designed and implemented by BSAs who are no longer at our company and we cannot find good documentation on it.

The end goal of this is to decrement inventory that we have billed a customer for via a different method.

Our current process:

• Create Inventory via a Work Order
• We do not sell that Item directly to the customer
• Instead, we have Billing and Retail Items set up in PIM that we use to bill the customers.
  • Sales Order is created with these other items, customer is invoiced