Hi, I recently used the Zed fares and loved it. What I loved about the Zed fares was the ability to fly on any airline that are within the Zed system without getting the tickets re-issued and purchasing multiple tickets. I suggest that you check to see what other airlines your parents may be able to fly on with their Zed tickets if they have to go to plan B or C. Also perhaps teach them how to call the airlines to list (sometimes, if the agents are busy at the airport, they direct you to call the 800 number to list rather than list you on a flight at the counter).

Hope they have fun