The Shopping Cart needs to be revamped from the get-go ... no old code. Redo it from scratch starting from the LISTING that is created by the Seller. No one knows better whether an item can be combined with other items, or not.
1) When creating a listing, there should be a toggle:
a) This item can be combined with other items
b) This item cannot be combined with other items
2) The buyer will see, on the listing, whether the item Can or Cannot be combined, and in the case of items that cannot be combined, THE ADD TO CART BUTTON IS NOT AVAILABLE or even shown AT ALL. Why should an Add to Cart function be enabled on a listing that the seller has already determined Cannot Be Combined? The reason the buyer should see the info that an item "Cannot Be Combined" is to prevent (or at least curtail) those "Can you combine this with other items?" questions from buyers.
3) Sellers should also be able to toggle Immediate Payment Required, OR NOT, depending on how they prefer to handle combined shipping, either an invoice sent after the buyer requests it, or a series of combined shipping rules setup by the seller, similar to how it is now.
4) The Request Invoice option should ALWAYS be available to the buyer whether the seller has set up Immediate Payment Required or not ... whose dumb idea was it to disable that on IPR items? If the buyer clicks the Request Invoice button, it overrides the IPR and allows the buyer to continue on with whatever he was doing, and the Seller gets a notification to send an invoice. The buyer gets a notification that an Invoice is Pending, and must be paid prior to shipment. Also, the seller should be able to be set how long he'll wait ... 24 hrs, 2 days, a week ... whatever ... and no payment results in an immediate cancellation WITH NO DEFECTS TO THE SELLER.
I'm ̶p̶r̶e̶t̶t̶y̶ ̶s̶u̶r̶e̶ certain the lunatics have taken over the asylum.
