You can add and/or modify tracking#, Quantity and Unit Price from your account page and here is how.
If there are multiple similar products, the tracking number will be useful information for warehouse to determine in the inspection process.
From the order list, click "Item" button. Item(s) in your order will show up
If you click on the links at Tracking#, Quantity and Unit Price, the box will show up.
You can then add or modify the value and click "Enter" on keyboard to update.
That' it!
Note:
Tracking# and Quantity can be modified only at Expected package status. And Unit Price can be modified before Prepare to ship.