In Project Accounting - Maintain Team Rosters - How do you create the Team Leaders?

In Project Accounting - Maintain Team Rosters - How do you create the Team Leaders?  It appears that the only place is setting them up as a MAS user which does not make sense.  Is this only used if you want a team lead to log in to MAS to approve the project? 

 

Can the approval not happen in the timesheet program?

 

Looking forward to your thoughts ;-)