Comic Michaela Watkins, who recently joined “Saturday Night Live,” has been cast in the romantic comedy “The Back-Up Plan” opposite Jennifer Lopez and Alex O’Loughlin. Watkins will play Mona, the longtime best friend of Lopez’s character, a fed-up wannabe mother who meets a promising romantic prospect the same day she receives artificial insemination. Kate Angelo (”Will & Grace”) wrote the screenplay, and Alan Poul (”Six Feet Under”) is directing. The movie will be CBS Films’ first feature release, set to hit theaters in January. Watkins is a member of the Groundlings comedy troupe. Her TV credits include “The New Adventures of Old Christine,” “Californication” and “Medium.” Her next feature is the comedy “The Prankster.”