He is not to be confused with his father, Kjeld, who runs the Steamscorch Mine and the settlement of Kynesgrove itself. He doesn't offer any special dialogue or interactions with the player, but seems wary of the Dragonborn's presence.
Should he die, his father will, after discovering his corpse, run into the Inn, where he will mourn over his death for a day.
Kjeld the Younger speaks with his mother, Iddra, about not abusing his sister, Froa (namely, his throwing of her into the goat pen) as well as him having to do chores that he believes she should help with. The sister is never seen in Kynesgrove.