Original sentence: David Miscavige (born April 30, 1960 in Philadelphia, Pennsylvania) is the American leader of the Church of Scientology and its many affiliated organizations, having assumed that role shortly after the death of Scientology founder L.Miscavige was an assistant to Hubbard (a "Commodore's messenger") while a teenager, and rose to leadership positions within the organization by the early 1980s
Edited sentence: David Miscavige (born April 30, 1960 in Philadelphia, Pennsylvania) is the leader of the Church of Scientology and its many affiliated organizations, having assumed that role shortly after the death of Scientology founder L.Miscavige, an American, was an assistant to Hubbard (a "Commodore's messenger") while a teenager, and rose to leadership positions within the organization by the early 1980s