Complex sentence: She had to change her name to join the Screen Actors Guild since there was another Amy Young registered and chose the name Bellamy as a tribute to her late father's best friend, Bill, who had helped to raise her after her father died.
Split into simpler sentences: She had to change her name to join the Screen Actors Guild since there was another Amy Young registered. She chose the name Bellamy as a tribute to her late father's best friend, Bill, who had helped to raise her after her father died.