Complex sentence: Gladys Bouvier was a character in The Simpsons--the aunt of Marge Simpson, Patty Bouvier, and Selma Bouvier, and the sister of Jacqueline Bouvier.
Split into simpler sentences: Gladys Bouvier was a character in The Simpsons. She was the aunt of Marge Simpson and Patty and Selma Bouvier, and the sister of Jacqueline Bouvier.