Who is Dr. and Mrs. Cohen from The Murderer's Daughters and what is their importance?

Mrs. Cohen is a social worker. She works at the orphanage where Merry and Lulu live, and over time, Lulu manipulates her into a growing relationship with the girls that ends with Mrs. Cohen and her husband taking Merry and Lulu as foster children. Mrs. Cohen is described as a kind woman, who spends a great deal of money on the girls. Unfortunately, the girls' fear of being sent back to the orphange interferes with them ever developing a closer relationship. In the end, Mrs. Cohen dies while both girls are away at school.