Auction Order Summary – add fields

I would appreciate any input on how to edit the order summary section. One key piece of information that is missing from the order summary is the “seller” user name. My auction site will allow for member postings. As such, I not only need to see who the buyer is….I also need to see who the seller is. I tried to do this in c-panel by adding “post_author” to the query, but it does not return any value. Since the item number on the order summary is linked to the post number, is there any way to link in the post author as the seller? I have included an example from another auction theme to show what I would like to see. Any help is greatly appreciated.

Angela