What is the importance of Lizbeth's diary in the novel, Other Birds?

Though it serves practical function, Lizbeth’s diary is also a symbol of her grief and pain. She is unwilling to let go of this grief and pain as long as the diary remains in play and unread, hoping that its stories will vindicate her and turn the world against her sister. Lizbeth’s eventual ability to let go of the past is prompted in part by Frasier’s refusal to act on the information in the diary, a refusal that both panics and releases Lizbeth.