Lawrence managed City to promotion in 2003 and was director of football at Bristol Rovers when Trollope managed them to promotion in 2008.
Recently, Lawrence, who managed Plymouth, Charlton, Middlesbrough, Grimsby, Bradford and Luton has been assistant to Dougie Freedman at Crystal Palace, Bolton and Nottingham Forest.
Young coach James Rowberry is also expected to be part of the coaching staff but there will be no place for Scott Young. The former City captain is expected to take up another role at the club away from the first team set up.