Who is Lotte from the memoir, All But My Life?

Lotte is a friend Gerda met at the Bokenhain labor camp. Lotte is the little girl who met her father for the first time when she was seven. Her parents reconciled and Lotte was overjoyed at the prospect of living with her mother and father. As she and her mother pack for their trip to join him in London, they get word that he died in a train wreck. Years later at the camp, Gerda sees her corpse dumped unceremoniously in a mass grave.