I used a $100 off Barclays discount and was able—painstakingly though—to refare the ticket and have the fare difference after price drop refunded to my wallet. The agent was very clear that this was the first time they’ve ever seen a Barclays discount code. I know, not the same as the 50% discount, but it seems that AS agents do have ways of working with at least the $100 discount to do things you can normally do with the BOA companion fares.