OT remark: Jesus. I work with the elderly, mostly. I would love to have her clarity of thought if and when I reach her age. I've heard before that playing chess retains hair loss and mental deterioration, especially in the elderly.
In the story world, the puzzle probably took its precise form from that game. If the game hadn't happened, maybe Anderssen's unpublished notes would have included a similar puzzle, or maybe nothing along those lines. So the coincidence is "merely" that she's related to the person who played the game that begot the puzzle.
I don't think I understand.