Bouncing back from a detour into television, Jon Robin Baitz is fast becoming one of the busiest playwrights in the country.In addition to adapting Robert Evans’ memoir, “The Kid Stays in the Picture,” for a planned Broadway bow, Baitz’s new play, “Love and Mercy,” is being positioned for a Rialto slot in the 2010-11 season. Set on Christmas Eve in Palm Springs, play revolves around a former matinee idol turned U.S. ambassador, his screenwriter wife and their novelist daughter. Prolific producing team Jeffrey Richards and Jerry Frankel (“August: Osage County,” “Race”) are heading the production. No cast or director has yet been announced. Play is described as an exploration of “the limits of parental love and filial duty, our myth-making culture, and the claim we have on our own biography when it involves the invasion of privacy of others.” Baitz’s many previous plays include “The Substance of Fire,” “The Film Society,” “Three Hotels,” “The Paris Letter” and “A Fair Country,” which was a Pulitzer Prize finalist. While his adaptation of “Hedda Gabler” transferred from Boston’s Huntington Theater to Broadway in 2001, “Love and Mercy” will mark the playwright’s Main Stem debut with an entirely new work. Baitz was creator and exec producer of ABC’s “Brothers and Sisters,” but stepped away from the show after its first season.