Complex sentence: Her grandparents were Edward Loomis Davenport and Fanny Vining Davenport who were 19th-century character actors; their daughter and Dorothy's aunt, Fanny Davenport, was considered one of the great actresses of the time.
Split into simpler sentences: Her grandparents were Edward Loomis Davenport and Fanny Vining Davenport, who were 19th-century character actors. Their daughter and Dorothy's aunt, Fanny Davenport, was considered one of the great actresses of the time.