Complex sentence: Maggie was promoted to Senior Constable in season 3 (1996) and was Acting Sergeant from Season 5 (1998) to season 6 then returned to Senior Constable when she returned from witness protection until she left in Season 7 (2000).
Split into simpler sentences: Maggie was promoted to Senior Constable in season 3 (1996) and was Acting Sergeant from Season 5 (1998) to season 6. Returned to Senior Constable when she returned from witness protection until she left in Season 7 (2000).