I have a request to provide the functionality to cancel/reverse a sales packing slip from the packing slip journal form via a button. It won't work to set the delivernow field to a negative qty and post because we typically have several packing slips for the same sales order. In the scenario if you have 3 posted pack slips (that have not been invoiced) and you post a negative qty, there is no guarantee which packing slip will have that qty reversed. So i want to be able to pass a specific packing slip id to reverse/cancel.