Mackenzie Phillips, who made headlines this week when she revealed an incestuous relationship with her musician father John Phillips, is returning to the Oprah Winfrey show tomorrow with her half-sister Chynna Phillips, has confirmed. Chynna will be live in the Chicago studio, while Mackenzie will appear via satellite. Mackenzie first revealed her explosive secret on Oprah’s show Wednesday. The sisters will not be on the whole hour. Oprah’s other guest will be Jay Leno.