I don't have my companion cert with me anymore because I already sent it in to for a flight. Can I Move Up using a connecting flight (instead of an originally scheduled non-stop)? I know that a connecting flight can be used as a Move-Up from a nonstop, but US is telling me that because my tickets were purchased with a companion cert, "the rules governing this type of ticket specifically states once travel has begun the city pairs must not change."

Considering that I am not changing my departing city nor my arrival city, how exactly would I be changing my city pairs?