Two sessions scheduled

Session A:- 2:30 to 4

Session B:- 3 to 4

If a client is scheduled to a session A initally. at 3 leaves session A and want's to join session B, he cannot.

Even though attendance has been marked for session A from 2:30 to 3, the system think's the client is still scheduled till 4 and hence does not allow to be associated with B