When importing a BOM, you generally want to keep it as simple as possible. Item No. and Quantity, maybe a Routing Link Code.
You either import the BOM directly onto the Production Order (doesn't make it usable in the future) or create a new Production BOM which makes it available for future production runs.
If you are trying to create the Production BOM (reusable), you need two tables, the Prod. BOM Header and Prod. BOM Lines. The Header is fairly basic, but needs to exist, and the Lines which is where the Items and Quantities will be imported. If you number your BOM Header based on the Parent Item Number, then as long as your Lines reference the Parent Number as the BOM Header you'll be in good shape.
Since the CAD system doesn't usually have the greatest formatting, it is often better to create a custom XML import which can have the logic needed to create the Header and Lines automatically. It will also better handle Items in the BOM that don't exist yet in Business Central.
Your partner should be able to assist you either way. I would suggest you reach out to them for some guidance.
