This kind of adding makes it easy to create a receiving invoice. If certain lines frequently appear in invoices and orders, they don't need to be entered each time you create an invoice; simply copy (add) them to the receiving document you are creating.
	Adding a sales order to a receiving document will not render the order fulfilled; in this sense, it is the same as adding a movement.

Although adding a sales order would seem to be identical to adding a purchase order, note the key difference: Unlike purchase orders, sales orders added this way are not considered fulfilled.

In terms of content, adding a sales order is the same as adding a movement; but in terms of form, it is the same as adding a purchase order.

The process for finding and selecting documents and lines to add is the same as with adding a purchase order to a receiving document.

In the Program Parameters (Settings | Program | Administration Panel | Settings | Program Parameters | Orders), you can specify whether the person responsible, linked document 1, or linked document 2 from the order will be copied to the invoice.