Complex sentence: Norma's old teacher, Miss Battersby, had had an affair with Andrew Restarick and bore Frances, and when she learned of Robert Orwell and his deception, she told her daughter, who found a way to become Orwell's co-conspirator.
Split into simpler sentences: Norma's old teacher, Miss Battersby, had had an affair with Andrew Restarick and bore Frances. When Miss Battersby learned of Robert Orwell and his deception, she told her daughter, who found a way to become Orwell's co-conspirator.