Originally Posted by
tobsw
Theoretically you can upgrade BA and AA operated flights on the JBA, IB marketed. They have to be bought through IB channels: web or service center.
However, this has to be done over the phone, AND importantly, has to be a flexible fare.
Do you have a link for that? I was looking at the upgrades section of "How to Use Avios" and it clearly stated that IB7XXX can't be upgraded, although I'm not sure how many codeshares fall under the JBA.