Accounting Entries when we Convert a Transfer Order into a Sales Order

Summary

We have a scenario where we are trying to initiate a Transfer order ( Inventory to Expense) and later convert the same to SO for Customer

Content

We have a scenario where we are trying to initiate a Transfer order ( Inventory to Expense) and later convert the same to SO for Customer . The transfer Order is created because the Requester is the Sales Rep for some of the DEMO/Prototype items which ultimately will be shipped to Customer without any invoicing 

I would like to know the best approach (Supply Order enrichment rules ,Process assignment Rule) and also the accounting flow for this kind of scenario , appreciate your thoughts