"Fredericka Elisabeth of Saxe-Eisenach (5 May 1669 - 12 November 1730), was a German noblewoman member of the House of Wettin and by marriage Duchess of Saxe-Weissenfels.
Born in Altenkirchen, she was the seventh of eight children born from the marriage of John George I, Duke of Saxe-Eisenach and Johannetta, Countess of Sayn-Wittgenstein-Sayn-Altenkirchen. From her seven older and younger siblings four survive adulthood: Eleonore Erdmuthe Luise (by her two marriages Margravine of Brandenburg-Ansbach and Electress of Saxony), Frederick August, Hereditary Prince of Saxe-Eisenach, John George II, Duke of Saxe-Eisenach and John William, Duke of Saxe-Eisenach." - (en.wikipedia.org 24.04.2021)