Who is Mrs. Brink from Affinity and what is their importance?

Mrs. Brink, a wealthy widow, lost her mother when she was very young. As an adult, she has become obsessed with communicating with her mother's spirit. Over time, Mrs. Brink has hired multiple mediums, who proved to be frauds and cheats. Selina Dawes, however, is believed to be the real thing, and Mrs. Dawes welcomes into her home and showers her with gifts and clothing.