Original sentence: The main character of Oates's story is Connie, a beautiful but somewhat irresponsible fifteen-year-old girl who is at odds with with her mother, herself once a beauty, and with her dutiful, "steady", and homely older sister
Edited sentence: The main character of Oates's story is Connie, a beautiful but somewhat irresponsible fifteen-year-old girl who is at odds with her mother, herself once a beauty, and with her dutiful, "steady", and homely older sister