Purchase Order can be generated for the Service Order products on backed order.
In the navigation
panepanel, go to Service then Service Orders
.Create your a service order. with products on back order
From the Service Order ribbon line which is located on the top panel. Click on button Purchase
You will be taken to the newly created purchase order screen
Expand title Show me Review and update the Purchase Order as needed e.g. increase QTY to be purchased
Expand title Show me Click on button Complete to process the purchase order
Expand title Show me Service Order shows the backed order back ordered part has been allocated and Percent Percentage Allocated is now 100%
Expand title Show me Fill in the Repaired Description
Click on button Complete to invoice the customer and complete the Service Order
Expand title Show me