SOP / POP - Save and Generate on a Sales Order for Direct to Customer Items only

Prior to saving a Sales order, we have ability to Save and Generate instead of just Save. The Save and Generate function saves the order and generates purchase orders for both Direct to Customer and Supplier Via (back to Back) orders for the preferred supplier. It currently groups both the Direct to Customer and Supplier Via (Back to Back) orders on to the same purchase order which is confusing for our suppliers. Is there a way to Save and Generate a purchase order for only Direct to Customer orders. Then we can use the Generate Order purchasing function for the Stock items and Supplier Via items.