Not sure about Six Flags, but Silver Dollar City in Branson, Mo. does the same thing. A few years ago, I bought a season pass for both my wife and myself. They sent me the pass, we went there, and had a great time. Soon after, I received a letter stating that I was not allowed to enter the park because I am a registrant and they returned my pass and money. However, they allowed my wife to visit. My money was good enough, but I wasn’t. Anyway, just a heads up.