I'm going to my workflow in order to describe the problem.
0) Find Screen - find by UserNumber - returns list of Invitations associated with that number. Find Screen Entity: Invitations
1) Invitation List - Join on Event and display event information for each invitation. List Screen Entity: Invitations
2) Clicking a list entry navigates to an event detail page. Invitee is joined to Event and more event information is displayed. Event Detail Screen Entity: Invitations
3) On the detail page is a button. Clicking this navigates to another List page with a list of Links for the event. Link List Screen Entity: Invitations - join on event, join event to Links, display link data
4) On the Links List page, clicking a row navigates to a detail page for that Link. Detail Screen Entity: Link - no way to join from Invitation to the actual link. Need primary key for link.
On the Link Detail page, I need to set up a "Home" button that returns to the original Event Detail button. However, I cannot add an Invitation filter to this page because its entity is Link. How do I set up a button that passes my original Invitation id back to the detail page?