Apply a Purchase Invoice to an Inventory

After adding a line to the Purchase, by double clicking on the Inventory field will open an Inventory Lookup. Most common Inventory items that would be linked to purchases are Labour and Vehicles, but purchases can be linked to any inventory item. 

Select the inventory item to link to the purchase: 

And complete the purchase as normal. After posting the purchase to the GL, the value on the line will be linked to the inventory item. Multiple lines can be linked to different inventory items as necessary. Once complete, going to the Inventory Management screen and opening the Purchasing tab on the appropriate inventory item will list all purchases that have been linked to the inventory item: 

Reports can be run by inventory item as well.