The Super-Sons have their most quintessentially 70s story in World’s Finest 224 (July/Aug 74), by Haney, Dillin and Colletta.
Superman and Batman and their sons are continuing to have generation gap issues, and agree to all attend a retreat in their normal identities. It’s a very commune type place, with all the awesome 70s touchy-feely exercises. Bruce and Clark both think this is all silly, while the juniors are far more into it.
The attempts they make at bond fail awkwardly, and the man running the place insists that they switch fathers. He claims to be correcting nature’s “mistake.”
So the heroes swap sons. There is another plot about a mysterious man who never speaks, and a nearby train wreck. When I first read the story I was terribly suspicious about the man in charge, feeling that he was playing the heroes and their sons for some nefarious goal.
In fact, there is no real villain in this story. The mystery man is a runaway android, who sacrifices himself to save the people from the train wreck. The guy in charge simply ordered the parent switch in order to get the fathers and sons to appreciate each other.