Ability to reduce quantity on a sales order when PLP has been raised

Requesting the ability to reduce the quantity on sales order lines when a Pick List proposal has been raised.  At present this function only exists for an increase in quantity if using either the notification listener or PLP robot.  A licence is required to close the existing PLP and reduce the quantity.  Would like the same functionality to reduce the quantity when requested to allow more flexibility on orders and the the PLP robot/ Notification listener to function the same way when reducing quantity as it does for an increase of quantity