The new ABC series focuses on a family who develop unusual powers after surviving a plane crash.
TV Guide says that Shepherd has now joined the cast as Barbara, the mother of Stephanie (Julie Benz).
Meanwhile, Bruce McGill has allegedly signed up to play Barbara's husband Alan.
Speaking about Alan and Barbara, Benz explained: "They don't know yet about what's happened to the family. So we have to decide if it's best to clue them in or keep them in the dark."
No Ordinary Family premieres on September 28 on ABC.