Script-writer and script editor.
Lefever's earliest scripts (written as Kelly Bermingham) were for television series Prisoner, for which she was both script-writer and storyliner between 1985 and 1986.
In the 1990s, Lefever wrote for a number of television series, including Pacific Drive (1996), The Adventures of the Bush Patrol (1996-1998), Neighbours (1998-1999), and Blue Heelers (1999-2000).
Since 2000, she has written for Something in the Air (2001-2002), All Saints (2004), Headland (2005), Home and Away (2003-2008), Stormworld (2009), City Homicide (2009-2010), and Miss Fisher's Murder Mysteries (2012).
In 2007, she co-created television series The Circuit: the series was nominated for three AFI Awards (for Best Telefeature or Mini Series, Best Screenplay in Television, and Best Television Drama series) in 2007 and 2010, as well as attracting nominations and winning AFI Awards for acting and direction.
Her work as script editor includes television series Blue Heelers (2002), telemovie Roy Hollsdotter Live (2003, written and directed by Matthew Saville), film The Black Balloon (2008, written by Elissa Down and Jimmy Jack, and directed by Elissa Down), and SBS series of short films by Indigenous film-makers Dramatically Black, including The Djarn Djarns (2005, written and directed by Wayne Blair) and Sa Black Thing (2005, written and directed by Rima Tamou).
Among Lefever's awards is an AWGIE Award for Television: Serial, for her episode of Something in the Air, 'All the Things I Should Have Said' (2002).