Heinz is Kerry's grown stepson, not child. In any case the story is that Heinz and Biden broke up their relationship over Ukraine: https://www.washingtonexaminer.com/politics/john-kerrys-son-cut-business-ties-with-hunter-biden-over-ukrainian-oil-deal
They will always be considered as their children by Pelosi, Biden, and Kerry.
The business relationship between Heinz and Biden broke up over Burisma in 2015, but they were partners in Rosemont Seneca Partners along with Archer since 2009. They were involved together on the China deal.