Lynda Bird Johnson Robb is the oldest living child of a U.S. President following the death of a United States Army officer who served as the United States Ambassador to where?
Lynda Bird Johnson Robb:  She is the oldest living child of a U.S. President following the death of John Eisenhower on December 21, 2013. John Eisenhower:  In the administration of President Richard Nixon (his father’s vice-president), he served as United States Ambassador to Belgium.
i don't know