The both of you should get a written clarification from DL. Show it to vayama if DL happens to deny instructing to cancel tickets.
I actually tried to get that from the DL rep. He said there was no way for him to email that confirmation as their system wasn't able to do that for third party cancellations. I don't want to sound gullible, but the agent was extremely knowledgable and helpful otherwise, so I don't doubt him. He seemed to imply that there would be a way to get that, it would just be a bit onerous. I'll wait and see how this develops in the coming days. It's early in the ballgame.
This sure has made an otherwise dull workweek exciting though, hasn't it? I've only needed 3-4 cups of coffee to stay awake.