Vanessa Kirby has joined the cast of “The Son,” Florian Zeller’s follow up to his Oscar-winning feature debut “The Father,” Variety has learned.Kirby, who was Oscar-nominated for “Pieces of a Woman,” will star in the film opposite Laura Dern and Hugh Jackman. As with “The Father,” “The Son” was adapted by Zeller and Christopher Hampton (“Dangerous Liaisons”), from Zeller’s critically acclaimed stage play.