I think I know why the invitaion tracking is getting lost, but I need help with a solution. Here is our scenario:

Users start a survey from an invitation. During the survey, we send them out to different custom web app we developed. We then return them to the Checkbox survey for some follow up questions. I am assuming the InvitationID is getting lost in this transition.

What would be the best solution to account for this? Store it in a hidden variable? Keep it and pass it back and forth between apps as query string? Other?

Thanks,
Tim