I'm pretty sure that you can change destinations within the same zone from the award, but changing the classification/type of ticket (even when the same points) if probably not available. You can call and ask, but I'd be pretty sure the answer would be no.

Before the plan ended you could have "returned" one and used the points to get another - I actually did that to return two Australia tickets and change then to North Asia tickets in early December because plans changed, but that was before the program hit the sunset date.