Complex sentence: After his death in 1994, his brother Peter succeeded him as chairman of the board, he served as chairman until his death in 2004, but not before his sons Edward and Paul had joined the board of directors.
Split into simpler sentences: After his death in 1994, his brother Peter succeeded him as chairman of the board. He served as chairman until his death in 2004, but not before his sons Edward and Paul had joined the board of directors.