Wild! I don't even know what flight I took pre-merger or how many years before the merger I got my account--must have been in my adolescence. Was a trip down memory lane when I started flying with United again and had to figure out my security answers from decades ago. I did not fly much for many, many years, and when I did other carriers always ended up being much cheaper on the few routes I'd take. The United rep told me they didn't see any other numbers attached to my account, but I did see my old number in my very, very prehistoric e-mail inbox. Maybe I'll try it out as an experiment sometime.