“One Big Happy,” a comic idea from “Party of Five” creators Chris Keyser and Amy Lippman to which Steve Martin and Diane Keaton are attached to star, is coming to the big screen folks.  I’d love to see Keaton and Martin together, again. They were great in “Father of the Bride,” although I am not partial to remakes. The story is hush-hush, but Variety describes “One Big Happy” as a family comedy about a couple and a family reconnecting amid various obstacles. The material is a strong match for Martin and Keaton. Keaton was last seen in the comedies “Mama’s Boy” and “Mad Money.” Martin next stars in “Pink Panther 2.”