Kitty and Robert make a life altering decision when the Presidential race takes a dramatic turn. Meanwhile, the Walker siblings are shocked by Nora’s reaction to a surprise proposal from Isaac, and Rebecca further investigates the identity of her father, when “Brothers & Sisters” returns to ABC, SUNDAY, APRIL 20 (10:02-11:00 p.m., ET), on the ABC Television Network. Guest starring are Ken Olin as David Caplan, Danny Glover as Isaac Marshall, Steven Weber as Graham Finch, Evie Peck as Gail and Bruno Oliver as the lab technician. “Separation Anxiety” was written by David Marshall Grant and Molly Newman and directed by Gloria Muzio.