@jonlutz79 The best way to do a many-to-many style of app is to have 3 sheets. Here is an example app that I put together for you and others to help understand the structure. It’s a very simple Events app, where you can sign up people to attend an event. Sign up can be done on the Events page/tab or the Participants page/tab. There is a list of Events and a list of possible Participants that are attending the Event. So 3 sheets. Events, Participants, Attendees. The Attendee sheet is the key to many to many relationships. I made it a template so you can copy the app and play with it. If you have any questions ask away.
All relations and lookups use Glides inside the builder relationship and lookup column creation in the Data section.
https://many2many.glideapp.io