Robert De Niro, Diane Keaton, Katherine Heigl and Amanda Seyfried will star in comedy The Big Wedding aka Gently Down The Stream, which Nu Image is pre-selling in Cannes.

Justin Zackham will direct from a script he wrote about a divorced couple who pretend to be happily married for the sake of their adopted son’s upcoming nuptials.

Zackham is producing with his Two Ton Films partner Clay Pecorin as well as Richard Salvatore and Harry Ufland. Millennium’s Avi Lerner, Danny Dimbort and Trevor Short serve as executive prodcuers.

Production on the Millennium Films and Two Ton collaboration is set  the middle of July in Greenwich, Connecticut.