Who is Aunt Ivy from Hattie Big Sky and what is their importance?

Aunt Ivy is the wife to Uncle Holt and is a mean-spirited and selfish woman. She is no direct relation to Hattie and resents Hattie's presence in their home. She agrees that Hattie will stay with them, but only until they can find someone who can put her to use. She manages to do so after Hattie has been with them for three years, making arrangements to send Hattie to work in a local boarding house for her keep. Thankfully, this event occurs at the same time as Uncle Chester's letter arrives.