First son Hunter Biden helped to arrange a dinner at the Chinese Embassy in Washington for a client of his now-defunct investment company — by working with a top Beijing diplomatic official he met at a January 2011 luncheon hosted by his father, then-Vice President Joe Biden, according to correspondence obtained by The Post and Fox News Digital. Hunter and Eric Schwerin, his former business associate at Rosemont Seneca Partners, assisted Marvin Lang — the managing director of Guardian Realty in Maryland — in setting up the dinner with Deng Hongbo, the embassy’s deputy chief of mission, on April 28,...