How can I give the seller one more chance to alter the total price of an order?
I am currently working on a e-commerce website, and the basic workflow is as follows,
1) shopper adds products into the shopping cart;
2) shopper submit the order without payment;
3) seller reviews the orders submitted by shoppers, and is able to modify the total price of the order;
4) seller releases the orders back to shoppers, which might have been modified;
5) shopper pay for the order.
Obviously, steps 2~4 are different from the regular process, and I am wondering how can I accomplish these steps.
Any suggestions how/where to start? Any existing modules that can be used for this purpose?
Thanks in advance for help.