Managed to get this working on our 3.6.3
- Created a test course - added two users, assigned one as a student and other as Manager
- Added the 'Managers Email' field in the user profile field in the 'Other fields' section (short name managersemail).
- Opened 'Edit Profile' page for student user and added the Manager user's email address
- Created an F-to-F activity, with approval required option checked. Added a session.
- Signed up on the activity with student user and I did not get the error/message.
- Both the student user and Manager user received an email confirmation of the booking
Hope it helps other people.
However, now trying to work out how to add the manager email detail to the respective 1000+ user accounts on our system