The show, which is based on the network's 2010 TV movie, stars Jennifer Love Hewitt as a housewife called Riley who begins running a massage parlour which is really a call-girl service after breaking up with her husband.
Shepherd has now signed up to reprise her role as Riley's mother, Deadline reports.
Shepherd's character will be called Lynette, though in the movie her name was Cassie.
Meanwhile, Deadline also reports that Kathleen York has landed a role in the series, which has been picked up for ten episodes.
York is expected to play Jolene, a masseuse at Riley's parlour.
Shepherd is probably best known for her roles in Moonlighting, The L Word and her own sitcom Cybill, while York has had roles in shows such as Dallas, The West Wing and The OC.
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