Not exactly concrete but..
https://conservativedailypost.com/exposed-sons-of-biden-and-kerry-struck-deal-with-chinese-officials/
Hunter Biden first met with Chinese leaders in 2011, along with a managing partner in Rosemont Seneca Partners LLC., Devon Archer. Also accompanying them was the nephew of infamous Irish-American Boston mobster Whitey Bulger, James Bulger. James Bulger controlled a Massachusetts-based consultancy firm at the time.
https://nypost.com/2018/03/15/inside-the-shady-private-equity-firm-run-by-kerry-and-bidens-kids/
Rosemont Seneca joined forces in doing business in China with another politically connected consultancy called the Thornton Group. The Massachusetts-based firm is headed by James Bulger, the nephew of the notorious mob hitman James “Whitey” Bulger. Whitey was the leader of the Winter Hill Gang, part of the South Boston mafia. Under indictment for 19 murders, he disappeared. He was later arrested, tried, and convicted.
James Bulger’s father, Whitey’s younger brother, Billy Bulger, serves on the board of directors of the Thornton Group. He was the longtime leader of the Massachusetts state Senate and, with their long overlap by state and by party, a political ally of Massachusetts Senator John Kerry.
Less than a year after opening Rosemont Seneca’s doors, Hunter Biden and Devon Archer were in China, having secured access at the highest levels. Thornton Group’s account of the meeting on their Chinese-language website was telling: Chinese executives “extended their warm welcome” to the “Thornton Group, with its US partner Rosemont Seneca chairman Hunter Biden (second son of the now Vice President Joe Biden).”
The purpose of the meetings was to “explore the possibility of commercial cooperation and opportunity.” Curiously, details about the meeting do not appear on their English-language website.
Also, according to the Thornton Group, the three Americans met with the largest and most powerful government fund leaders in China — even though Rosemont was both new and small.
The timing of this meeting was also curious. It occurred just hours before Hunter Biden’s father, the vice president, met with Chinese President Hu in Washington as part of the Nuclear Security Summit.