When a finished good has more than one build material (BOM), Luminous automatically uses the first one that was saved — there is no separate "primary" or priority flag.

Short answer

If a SKU has multiple build materials, the default on a new work order is the one that was saved first. To make a specific recipe the default, save it first. You can always pick a different build material for any individual job.

How to control which build material is used

  • Set the default: save your build materials in priority order on the finished-good SKU — the first saved becomes the default.
  • Override on a single work order: choose the build material on the work order create form.
  • Override inside a production run: in the run's By Product view, change the build material for a line (you can also double-click a component line during planning to switch it).

This only affects which recipe pre-fills; it never prevents you from selecting another.

Still stuck? Contact support if the build material you expect is not available to select on a work order.