Elfman will play Billie, a San Francisco film critic whose film with a much younger man leads to pregnancy and the start of a new wacky family.
CBS had picked up the pilot with a cast-contingency, which has now been lifted.
A three-time Emmy nominee for "Dharma & Greg," Elfman's recent TV appearances include guest spots on "My Name Is Earl" and "Brothers & Sisters," plus the very short-lived "Courting Alex."
Over at ABC, Smart has snagged the title role in "See Cate Run," the "Jack & Bobby"-esque legal series that had previously been called "I, Claudia." [Yes, we also prefer "I, Claudia."
The pilot focuses on a smart young prosecuting attorney who doesn't know that someday she'll be a candidate for the US presidency.
Smart, who will next be seen in "Crank 2: High Voltage," starred in the pilot "The Meant to Be's" last development season. The "Mirrors" and "Varsity Blues" star's other TV credits include "Smith," "Scrubs" and "Felicity."
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