Originally Posted by
tardyturtle
Others can chime in, but my understanding based on previous posts is that his companion upgrade would be cancelled if you cancel your ticket. I believe if you get him into a preferred seat (eg exit row) using your status that he may be able to keep that.
Haven't there been reports of C+ "upgraded" seats being kept? I wouldn't expect a free FC upgrade to be retained.
Any change is likely to result in a shuffling of seat assignments--even a minor schedule change by a few minutes or a change of flight number--and in that case even preferred seats are likely to be lost. This will surely happen if there's a change of aircraft type, even if the same seats are classified as being of the same category on the new aircraft.