With such a purchasing process:
- Create the purchase order.
- Sends the purchase order, generates the delivery note.
- It creates a purchase invoice of the same supplier and brings the lines of the delivery note or delivery notes, that these lines if they have the field Nº of order filled.
- It registers the invoice.

Until the delivery note if we can have the follow-up of the purchase order, but once registered the invoice we lose it, that is to say if we accede to Navigate --> Invoices from the menu of purchase orders, it does not bring us the information that this in a hist. purchase invoice and in the lines of the hist. if it contains the information.

The problem is at the time of navigating, it should look for the order in the lines not in the header, since if it comes informed. Otherwise the utility to make invoice and to bring delivery notes does not keep the traceability of Order - Delivery note - Invoice. Since the header comes empty, however the lines if they bring the order Nº, in delivery notes and invoices.