The Enchanted Swans by Christy Nicholas
How does one choose between love and duty?
Based on an ancient Irish fairy tale, The Children of Lir.
Fionnuala is the eldest of four, and the only girl. She knows her duty well, and must take care of her siblings, a promise she made to her dying mother. But when her father marries their dead mother’s sister, jealousy and sorcery take over their home in ancient Ireland.