EXCLUSIVE: Diane Keaton is attached to star in The Most Wonderful Time for Relativity Media. President of Relativity International Camela Galano has launched sales on the Croisette.

Jessie Nelson will direct from a screenplay by Steven Rogers and Brian Grazer, Ron Howard, Kim Roth and Nelson will produce with Relativity.

The executive producer roster includes Relativity president Tucker Tooley, Ron Burkle, Jason Colbeck and Rogers.

The Most Wonderful Time centres on Charlotte and Sam, a longtime couple on the verge of separation who stage what they believe will be a final Christmas celebration with the family.

When the dysfunctional brood gathers at the homestead and a shocking episode occurs, Charlotte and Sam question their decision. 

Relativity president of production Robbie Brenner will oversee the project for the studio.

Nelson is represented by WME and his directing credits include I Am Sam and Stepmom, while Rogers previously wrote PS I Love You and Kate & Leopold. He is represented by The Gersh Agency.