Adding SKU to individuals options?

Anyone have any ideas of the best way to add UPC's to product options? I have dug around the files and am still trying to determine the best route to take with this. When dealing with amazon and drop ship companies, your feed must show the different UPC for each product option if there is a difference in size or color.

Basically, I need to show UPC's for each size of each shirt for my wholesale site. In order to save space on the site, I am creating a new product for each shirt color. But for sizes, I am adding them as 'Options'. See MobiusApparel.com/wholesale to see how everything is laid out.

Should I just delete the UPC link "'upc'=> $query->row['upc']," product.php and place it within the "options" string?
I need each option to allow a different UPC.

Thanks in advanced.

Running Version 2.0.1.1

please look in the extension section

http://www.opencart.com/index.php?route ... tion%20sku

All of these are for SKU add on. I am looking to add UPC's to each option of a product. A will also need the different UPC's to for each option (I.e. Small, Medium, Large) to show up in google feed.

Looking at it now, I think I am going to remove the UPC input on the data page and figure out how to add the UPC to the options instead.

What I am looking for is when I add a shirt to my store, the option field has an input UPC for each individual option for my sizes.

Did you find a solution already?