Definitions of shipment page

Courier fees: the fees that you get for your service
Package fees: You sender can request from you to collect money for him and send it back to him after delivery, this money is the package fees.
Return courier fees: the fees if you need to return something to the sender again like the above example.
Return package cost: just for the system and removed for customer.
Return package fees responsible: when returning a collected money from receiver to the customer the fees for this action who will pay for it ? The receiver or the sender.