Who is Beatrice Gilcrest from Pictures of Hollis Woods and what is their importance?

Beatrice Gilcrest is Josie's cousin and best friend. She travels to New Mexico to draw, but she is worried when she cannot reach either Josie or Hollis by phone. When Hollis telephones from Branches to tell Beatrice that the agency is making Hollis leave, Beatrice agrees to come home and move in with Josie.