Hopefully you are aware of this, but AVL is only 100 miles / 2 hours drive from CLT, which has several AA flights from LHR every day and they are BA codeshared. So it wouldn't surprise me if there aren't many codeshare options to AVL. There are connections via NYC and WAS on AA, as well as CLT, but they would be to LGA and DCA so not convenient for a London routing. Hence CLT-AVL is your most realistic option, with PHL and DFW as poorly timed alternatives.