addUserToStay - sends an email, updates user and stay, invalidates old stays stayOver - changes stay, room, and user
Sometimes required, but I think in general it is much better to put the decision making on the ui.
setupDevice - based on field "replacementDevice" - UI should guide through decision
Order is the largest thing to refactor, as it's currently serving many purposes: Hotel Service Requests, Experience Reservations, and Guest UI.