I assume you are talking about being picked as the Grand Marshall that leads off the parade. That is simply luck of the draw. There is a Grand Marshall Liason that circulates through Main Street through the morning just talking to people, you would never even know what their purpose is as they are dressed like any manager and basically creating idol chit chat as any CM would. When they get the vibe from a family that they think would be interested and enjoy the experience then they ask them. Right place at the right time...