According to her Wikipedia article, Karoline Mathilde’s mother was Princess Adelheid of Hohenlohe-Langenburg who was the daughter of Feodora of Leiningen. Her older sister Auguste Victoria married Kaiser Wilhelm II. She had daughters Victoria Adelheid, Alexandra Victoria, Helene Adelaide, Adelheid Luise, and Karoline Mathilde.
From Miss Mertens' photostream on flickr. I tried various tricks to tease details out of the dark areas, but none worked so the only change I made to the original is removing the sepia tone.