Terry Strada, a leader of the group 9/11 Families & Survivors United for Justice Against Terrorism, will mourn again this year, but not at the site where the towers once stood and her husband died. She plans to attend “a private service” at the Shrine of St. Joseph in Stirling, New Jersey, which she said has “a beautiful and solemn space” dedicated to all who died in the 9/11 attacks. But she is also full of fury at the government’s refusal to release all it knows about the run-up to the attacks. “It’s very sad that we’re still being kept...