Princess Caroline of Nassau-Usingen was the elder daughter of Karl Wilhelm, Prince of Nassau-Usingen, and wife of Landgrave Frederick of Hesse-Kassel.

Mary of Great Britain was the second-youngest daughter of George II of Great Britain and his wife, Caroline of Ansbach, and Landgravine of Hesse-Kassel as the wife of Frederick II, Landgrave of Hesse-Kassel.