Skylight confession (2007) by Alice Hoffman

Red haired Arlyn met her husband after her father dies. Fate brought the man to her house.  She then perused him at the university and his home.  They married. Then her 6 year old son, Sam, dis poorly after she dies of cancer.  But Arlyn's ghost appeared to the father and to the new nanny, who kept the family together.  Blanca loved her brother Sam, even though she was 6 ears younger, Sam became a drug addict while years later Blanca discovered that her "father'' was not her father.  Sam lost his life to drugs.