On the morning of Sept. 11 last year, about two dozen family members of those killed in the terror attacks filed into the White House to visit with President Trump. It was a choreographed, somewhat stiff encounter, in which each family walked to the center of the Blue Room to share a moment of conversation with Trump and the first lady, Melania Trump, before having a photograph taken with the first couple. Still, it was an opportunity the visitors were determined not to squander.