https://disneyworld.disney.go.com/guest-services/rider-switch/ said:
To Use Rider Switch:
1. First check with a Cast member to see if Rider Switch is offered at the attraction in question.
2. Once at the attraction, approach the greeting Cast Member with your entire party. At least one adult member of your party and the Guests who are not riding will be issued a Ride Switch entitlement by the Cast Member and asked to wait in a designated area (usually outside of the attraction). This group is “Party 2.”
3. The other party members (“Party 1”) ride the attraction.
4. After riding the attraction, Party 1 locates Party 2. Then, Party 1 takes over supervision of the non-riding children or Guests.
5. Party 2 enters and boards the attraction without having to wait in the regular queue a second time. The Rider Switch entitlement must be validated by a Cast Member at this time.
If the person in Party 2 waited alone with the child, he or she may bring up to 2 other Guests back to ride the attraction with him or her. Please note that only 3 Guests are allowed per Rider Switch Pass.