Sometimes one has to research in circles.
If the parent-child connection between Ira and Clark is weak, some would say to research Ira and Clark more aggressively, leaving no stone or record unturned. And sometimes we need to do that. But if Clark's parents are known and Clark's siblings are known, going through their information may give me a clue to strengthen the Ira-Clark relationship.
Or there could be a will or probate for a grandparent, an aunt or an uncle that makes everything clear. Something I might miss if I only focus on Clark and Ira.