Minimum quantity for a BOM

I have created a BOM and entered a quantity of 4 pieces to be produced.

A client orders 1 piece of this item to be produced. In the production planning, I pull in the items to be produced from the sales orders.

Since there is only one item ordered, ERPNext tries to create a work order for only 1 item. We produce in batches, and a batch always produces multiples of 4 pieces, so any other value would not be possible.

How can I default a minimum value to be defined in the production plan, instead of producing exactly to order?

EDIT: And why does ERPNext create two separate entries for Sub Assembly Items? Wouldn’t that be more logical to combine the values to a single entry?