You can view existing team participants by selecting 'Total Participants' from the right hand panel when viewing a team in the web interface. In the app, participants are shown in the team view automatically.
Participants can also be viewed, configured and removed from the team using the action buttons in this list or by swiping to remove in the app.
In the web interface, clicking 'Update team participants' allows new participants to be added or removed by checking or unchecking the checkbox for each participant. Only current event participants can be added to an event team.
If an expected participant does not show up in the list, check that they have been added to the overall event.