Complex sentence: Whitehurst defied an order to burn the diaries, instead he followed the advice of a South Vietnamese translator and kept them for 35 years, with the intention of eventually returning them to Dang's family, if possible.
Split into simpler sentences: Whitehurst defied an order to burn the diaries, instead following the advice of a South Vietnamese translator who advised him not to destroy them. He kept them for 35 years, with the intention of eventually returning them to Dang's family, if possible.