Bills of Material - Intermediate Stock States

We’ve started inputting our Bills of Material in full, wherein a stock item goes through several processes. In actual fact these processes rarely happen all at once, so we have stock in varying states.
We need to be able to record what stock we have in what state, obviously. I can’t see any way of achieving this without having each state as a separate item, and breaking the Bills of Material up into their component stages.

Please can anyone tell me if I’m missing something?

You are correct, you need to have different items for the different states.