Production on the tentatively titled “The Wedding” a.k.a. “Gently Down The Stream” and the “The Big Wedding” has begun in Greenwich, Connecticut. The comedy, which will see Katherine Heigl join an all star cast that includes Robert De Niro, Diane Keaton, Robin Williams, Susan Sarandon, Amanda Seyfried, Topher Grace and Ben Barnes, is scheduled to shoot throughout August producer Clay Pecorin told Greenwich Time today.