Setting up a purchase order payment process

-- HikaShop version -- : 3.1.1
-- Joomla version -- : 3.7.3
-- PHP version -- : 7.0.19
-- Browser(s) name and version -- : FireFox 53.0.3

I need to be able to add the ability for a customer to place items in a cart that gets saved, but then allow a supervisor (possibly posing as the vendor) to access the order and finish it with a Purchase Order number. How would I go about setting this up?

Yes, I figured out how to turn the cart into an order with a status of just "created". But what I need to figure is a way for someone else with higher privledges to go into HikaMarket and add a Purchase Order number when they change the status to "confirmed". I've added a custom field (PO/Comments) to the order table but cant figure out how to make it editable in HikaMarket.

The whole reason is that I need a method where a customer's junior employees can order items by creating an "Order", but then the customer's senior employee could login to approve the order by adding a purchase order # and changing its status.

Thanks for the help! Your extensions rock!!