The user who checks and posts the pending vendor invoice should have the possibility to change the Number sequence group on the header of the pending invoice.
At the moment, the user must go back to the purchase order, change that information, confirm again the order and generate again the invoice.
But because of segregation issue, often the user who checks and posts the invoice (administration office) do not have the permission to modify the purchase orders, moreover this information (number sequence group) is typically in charge of the administration office.
Moreover, in Italian companies, the number sequence group vehicles the Sales tax book section where the invoice must be posted for VAT declaration purpose. So it's important to be able to change the NSG on the pending invoice.