Complex sentence: Kazooie was not to be featured as a main character in "Project Dream"; she was initially going to have an appearance as a baby bird found by a girl named Ella, who was Edison's younger sister.
Split into simpler sentences: Kazooie was not to be featured as a main character in "Project Dream". She was going to have an appearance as a baby bird found by a girl named Ella, who was the protagonists' younger sister.