[spoiler]Daphne in RT 1840 was the sister of JoAnna, Quentin's late mistress. Daphne arrives to take the position of governess, but she is really there to avenge her sister. She plans to kill Quentin because she believes he killed JoAnna. In PT 1841 she plays Catherine's sister; she marries Bramwell, but then she becomes ill and dies.
I always thought she was supposed to be Catherine's younger sister.[/spoiler]
[spoiler]I totally forgot she was Joanna's sister! But then, Lee Beery was so AWFUL as Joanna, I may have just blocked her out, LOL!
Daphne in 1841 PT *was* the younger sister to Catherine, by quite a few years guessing by the fact that Catherine chastize's Bramwell for marrying her and her being "just a child" etc...[/spoiler]