This has been brought up in the past and honestly  I am surprised people are managing without any ability to put a discount or negative value in a purchase order.

We are constantly having some credit for a past order or a bulk discount or many other reasons to reduce the total on a purchase order.

A simple option would be to allow negative additional costs, tho line discounts would also be ideal.

This is a great idea. I was thinking the same thing. I am coming from another platform that allows this and the creation of Credit Notes. Both of these need to be added so that Linnworks as a better PO system.