> But she would have been just three years old at the time of Lincoln's funeral, and while her family and the Roosevelt's family socialized together, even her quoted reminiscence is less than definitive about whether that's actually TR.

While she might not have direct memory of the event, it would not be unheard of for older relatives to explain the picture to her when she was older. Just because she doesn't remember it directly does not automatically make the story of the picture untrue.