During her marriage, Daisy, known in German as the Fürstin von Pless, became a social reformer and militated for peace with her friends William II, German Emperor and King Edward VII of the United Kingdom.
Daisy's brother George in 1900 married Jennie Churchill, the mother of Winston Churchill, as his first wife, and after their divorce married in 1914 Mrs. Patrick Campbell, the actress, as his second.