Happy to try and help clarify.
You stated you have a BOM for a unit (i.e. “finished good”.) You stated you also have a BOM within that BOM. In Cetec we call this a “subassembly”. Within that subassembly you have some number of raw components. You are stating that those components are not decrementing from your inventory when you ship the BUILD order for the top-level finished good BOM.
That leads to a question. The raw components will only decrement from inventory if they are first picked on the BUILD work order. Are you explicitly picking those raw components?
Or, are you instead picking the PCB subassembly part number only? And, if so, how are you getting the PCB subassembly part number available in stock to pick in the first place?
There are two options here: 1- you could create a discrete work order for the subassembly, and build that subassembly into finished subassembly stock first, so that it becomes available for you to pick it on the top-level work order. “Complete/Receiving” this work order would decrement the component inventory; 2- you could set the subassembly to “with top” at the time of order entry. I will include a screenshot below to show you where to find that (it’s on the Commit To Order page of a quote). This will have the effect of, on the pick list for the top-level work order, replacing the subassembly prcpart with the components that make up the subassembly prcpart, so that you can pick them, so they can ultimately be relieved from inventory.
Here is the screenshot of the “with top” option:
If you leave the setting set at Build? “YES” it will create the work order for the subassembly, and you’ll want to pick that and complete/receive it first (option #1 described above).
If you put the setting at Build? “With Top”, it will behave according to option #2 described above.
I hope this helps clarify things for you!
For further assistance, you could review this how-to tutorial: http://cetecerp.com/support/how-to/multi-level-bom-work-order-entry.html