Originally Posted by BobOscar

If she doesn't cancel her ticket on the return, the husband will get get the upgrade since they won't know she's not flying. If she cancels way before the flight, his benefits will probably be cancelled.

I had to miss a flight one day that my wife & I were both upgraded on (based on my status) and since I didn't cancel until right before the outbound flights, she kept her first class seats on both outbound flights. When I called to "cancel" I was actually changing to later flights for me that day.

So the best strategy is to either not cancel, or cancel right before the flight leaves.