When Infinity Incorporated was first launched, the opening storyline sent the Infinitors back in time to meet their parents in their prime. What would you think of such a solution for the Infinitor generation on Primary Earth? That is, if Alan Scott is too young to have fully grown children when the JSA arrives in the present, have Jade and Obsidian be time travelers from a possible future who have been sent to the present to help the JSA. Likewise with Rick Tyler, Jesse Chambers, Tom Bronson, and so on.
And then there's the trio that's difficult to handle for a whole different reason: Power Girl, Huntress, and Fury. Here, the problem isn't with their parents being too young to have grown-up children; the problem is that their parents don't exist