This question concerns the use of product variants in creating BoM's in the manufacturing & PLM module in Odoo v13.

When the creation of product variants is set to 'dynamic', these variants only get activated when a PO or SO containing an order line with this product is confirmed.

But in the Manufacturing module, or in the PLM module, BoM's need to be created in preparation of the actual manufacturing execution. How can I add a product variant that has not yet been part of a confirmed SO or PO, as a component of a BoM?