Currently, there is no way to add "part number or id" number to any online cart reports.  This is basic eCommerce information and should be readily available.  Add part number to eTap item records. Add part number to Standard Cart Items Remaining Report. and (optionally) to order details.  Also, create Packing List standard report that includes account information, item description, part number (optional),  qty, shipping method, and a blank check box (for the packer to manually tick off).   Attached are existing standard report images.   

Standard Report...

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