It can be a little tricky to work out how to navigate the many to many relationships between Dataverse tables
Let’s look at the many-to-many relationship between the Teams and User tables. A Team can have many users and a User can belong to many teams
The key to being able to traverse the relationship is to find the name of the many to many relationship between the 2 tables. This can be identified from either table
Very useful post. I’m wondering if from my powerapps app, i can add members to a user/owner team based on selection of emails from a combobox?
Yes, that is possible. Either access the teammembership table directly from your Power App to create the records, or use a flow. Ensure the app user or flow owner has the necessary security roles assigned to access and write to the table.