When in Okay for Now does Lucas tell Doug that Lieutenant Merriam is MIA?

In Gary Schmidt's 2011 young adult novel, Okay for Now, the protagonist, Doug Swieteck, is one of three boys. The oldest is overseas fighting in the Vietnam war at the start of the novel, but Doug reports that he, like the middle brother, is often antagonistic. In fact, Doug's memory of Lucas is so strong that it inspires Doug to be a better person so as not to avoid Lucas's fate and reputation as a bully.
In chapter 6 (of ten total chapters) Lucas returns from war. He has no legs and is nearly blind. He is self-loathing and remains depressed for several months, until (in chapter 7) he visits the library where the librarian asks if he knows her husband. Lucas lies and reports that he does not, but later reveals to his brothers that her husband is MIA.
Meeting the librarian is a major turning point for Lucas, as he realizes that he is lucky to be alive. By the novel's end, he will end up as an assistant coach (under the direction of Doug's P.E. teacher, also a war veteran). Lucas becomes respected by his students and overall happier.

Lucas divulges the news about Lieutenant Merriam at the very end of chapter 7. Doug, Lucas, and Christopher visit the library; the librarian Mrs. Merriam welcomes Lucas home and asks if he knows anything about Lieutenant Leonard Merriam, to which Lucas answers no. He knows, however, that the lieutenant is missing in action. He tells his brothers the news while looking at the Audubon illustrations that Doug has been copying. Lucas recognizes how fortunate he is to be able to come home, if not entirely in one piece. This point is driven home when Mrs. Merriam greets him; though Lucas cannot see well, he probably senses the fact that the librarian is in pain, knowing that he returned from Saigon but her husband did not.