The Fortunate Ones by Ellen Umansky

Wow. What a story! Children sent by their desperate parents to England to be raised by strangers all to escape Hitler's genocide. Two Austrian Jewish siblings reside with different families, separated from each other, their parents, their country of origin. Rose endures loneliness and loss over the many years of the war, and after the war upon learning that her parents died likely in a Concentration camp becomes absorbed with tracking down a painting her mother loved, and she remembers so well from their home.