When you add a game to your gaming group must be a "base" game (example: Sid Meier's Civilization: The Board Game).
Then, if there are any expansion for this game, the web must ask for possible expansions that you have (example: "Fame and Fortune" or "Wisdom and Warfare") to choose any of them.
When you add a play with a game with expansions, you can add any expansion for that particular played game and register as a data to make better stats.