FM - GR Passenger (Pair of SUR - FM passenger) will run as GR - SUR passenger in the evening. And GTL - GR Passenger (Pair of SUR - GTL passenger) will run as GR - WADI passenger in the night and the same train run as WADI - SUR Passenger in the next morning. I think this arrangement is done keeping in mind the regular commuters (office goers) in the morning/evening.