Who is Catherine Creek from The Grass Harp and what is their importance?

Catherine Creek joined Dolly's family as a child and is Dolly's best friend. She was orphaned at an early age, and as an adult lives in a small home on the Talbo property. Catherine is very involved in the Talbo's family life and is considered a part of the family. She also plays a large part in Collin's upbringing.