looks to me as though they decided they needed to do the son as well. perhaps he was getting to be a problem in their coverup of doing the father;

John Fitzgerald Kennedy, Jr. (1960-1999), who was often referred to as “John John,” was an American lawyer, journalist, magazine publisher and the only son of assassinated U.S. President John F. Kennedy (1917-1963) and First Lady Jacqueline Kennedy, often referred to as “Jackie.” Jr. died in 1999 at the young age of 39 while piloting a small plane.
Most Americans had long expected and perhaps even hoped that JFK’s handsome and charismatic son would continue the Kennedy family dynasty and perhaps follow his slain father’s political footsteps.
John John was one the last remaining vestiges of the true anti-war Progressive Movement, which has since been bastardized, corrupted and all but disappeared in recent years. Notably, another leading anti-war Progressive, Sen. Paul Wellstone, also died in a highly suspicious light-plane “accident” in 2002- three years after JFK, Jr.
Was the creator and publisher of the magazine George, which was a blend of politics, history, society and celebrity culture. In 1998, John John conducted a major interview with Oliver Stone, who produced and directed the 1991 hit film “JFK” that challenged the official narratives surrounding the assassination of the president. JFK’s widow Jackie was unable to prove it but always felt there was a larger conspiracy involving her husband’s murder.
https://www.winterwatch.net/2018/11/re-examining-the-untimely-death-of-a-presidents-son-john-f-kennedy-jr/