Improve purchase orders

There is a desire that if a purchase order is created, that payment terms can be linked to it. These payment terms are not part of the contract sum of the project itself, but only linked to the purchase order. These are not payment terms that must be sent to the relation/client, but should give an indication to the subcontractor what amounts they should use when they send an invoice and how many terms are eventually linked to the subcontractor.

Once these are created and the subcontractor sends the purchase invoices, when booking the purchase invoice it should be possible to select a purchase order and if the purchase order is selected there should also be an option to select a payment term. This gives clear overview in which purchase order/payment term the purchase invoice is linked to. With the purchase order you should then also be able to clearly see which invoices/ instalments have already been paid.