Cloudy Jewel by Grace Livingston Hill

Julia Cloud, the oldest--and most responsible--child of her family, helped raise her four siblings due to their mother's long-time illness and father's death. After faithfully nursing two ill brothers (who died), she then cared for her invalid mother for many years. When Julia's mother passes on, her only surviving sibling Ellen fully expects--and nearly demands--that her spinster sister come live with her family. But to earn her keep, Julia must be their live-in housekeeper and babysitter for Ellen's four children. But Julia's college-age niece and nephew arrive unexpectedly from California and offer Aunt Cloudy Jewel a surprise opportunity she never expected in her wildest dreams.