Now James and Lachlan Murdoch, octogenarian media baron Rupert’s only sons, are teaming up at the helm of Twenty-First Century Fox Inc (FOXA.O), the crown jewel of the empire their father built. James Murdoch, 42, is set to be elevated to chief executive of the entertainment company that is home to “The Simpsons” and movie franchises like “Planet of the Apes.” Lachlan, 43, will become co-executive chairman with his father as executive chair, a source familiar with the situation said on Thursday, describing the arrangement as a partnership between the brothers.