@vincent56 @bablbooks is something like this what you are looking to have in your app?
Preview:
https://forum_app.bubbleapps.io/version-test/nested_rgroup
Editor:
In this forum example, there is a a List of Documents within the User. One way to have each Document separated into cells is to use a nested repeating group. To do this, you’d created one repeating group which does a search for Users. Within that repeating group’s first cell is another repeating group (type: Document, Data Source: Current cell User’s List of Documents). Then you can place a text element with the dynamic expression “Current cell’s Documents Title” in the first cell, and a download icon (or anything of your choice). An alternative (on the right side) is to have a Repeating Group displaying Documents, and the Data Source is determined by the Dropdown of User’s values. The data source for it would then be “Dropdown Select a User’s List of Documents”. If you need any help setting this up in your app please feel free to let me know. 