Question: Who is John George Ii, Duke Of Saxe-Eisenach's father-in-law?

Knowledge 1: John George II, Duke of Saxe-Eisenach
Johann Georg II, Duke of Saxe-Eisenach (Friedewald, 24 July 1665 – Eisenach, 10 November 1698), was a duke of Saxe-Eisenach.He was the second son ofJohann Georg I, Duke of Saxe-Eisenach and Johannetta of Sayn-Wittgenstein.The death of his older brother, Frederick August—who was killed in battle in 1684—make himthe new heir of the duchy of Saxe-Eisenach.Two years later (1686), Johann Georg succeeded his father when he died.In Kirchheim unter Teck on 20 September 1688 Johann Georg married with Sophie Charlotte of Württemberg.This union was childless.When his cousin, the young Duke Johann Wilhelm of Saxe-Jena died (1690)Johann Georg inherited a part of his duchy, because he was compelled to make a divisionary treaty with the Duke Wilhelm Ernst of Saxe-Weimar, his other cousin and brother-in-law of the late duke.Johann Georg died suddenly of smallpox, and was succeeded by his brother, Johann Wilhelm. [SEP] Knowledge 2: Sophie Charlotte of Württemberg
Sophie Charlotte of Württemberg (22 February 1671 – 11 September 1717), was a German noblewoman member of the House of Württemberg and by marriage Duchess of Saxe-Eisenach.Born in Stuttgart, she was the ninth of eleven children of Eberhard III, Duke of Württemberg and his second wife, Countess Marie Dorothea Sophie of Oettingen-Oettingen.From Sophie Charlotte's ten full-siblings, only she and his three (unmarried) brothers George Frederick, Louis and John Frederick survive adulthood; in addition, they had fourteen older half-siblings from their father's first marriage with Anna Katharina, Wild- and Rheingräfin of Salm-Kyrburg, of whom only eight survived:Sophie Louise (by marriage Margravine of Brandenburg-Bayreuth), Christine Fredericka (by marriage Duchess of Oettingen-Oettingen), Christine Charlotte (by marriage Princess of East Frisia), William Louis, Duke of Württemberg, Anna Katharine (unmarried), Eberhardine Katharine (by marriage Duchess of Oettingen-Oettingen), Frederick Charles, Duke of Württemberg-Winnental and Karl Maximilian (unmarried).
Knowledge 1: Sophie Charlotte of Württemberg
Sophie Charlotte of Württemberg (22 February 1671 – 11 September 1717), was a German noblewoman member of the House of Württemberg and by marriage Duchess of Saxe-Eisenach.Born in Stuttgart, she was the ninth of eleven children of Eberhard III, Duke of Württemberg and his second wife, Countess Marie Dorothea Sophie of Oettingen-Oettingen.From Sophie Charlotte's ten full-siblings, only she and his three (unmarried) brothers George Frederick, Louis and John Frederick survive adulthood; in addition, they had fourteen older half-siblings from their father's first marriage with Anna Katharina, Wild- and Rheingräfin of Salm-Kyrburg, of whom only eight survived:Sophie Louise (by marriage Margravine of Brandenburg-Bayreuth), Christine Fredericka (by marriage Duchess of Oettingen-Oettingen), Christine Charlotte (by marriage Princess of East Frisia), William Louis, Duke of Württemberg, Anna Katharine (unmarried), Eberhardine Katharine (by marriage Duchess of Oettingen-Oettingen), Frederick Charles, Duke of Württemberg-Winnental and Karl Maximilian (unmarried). [SEP] Knowledge 2: Christian III Maurice, Duke of Saxe-Merseburg
Christian III Maurice, Duke of Saxe-Merseburg (Merseburg, 7 November 1680 – Merseburg, 14 November 1694), was a duke of Saxe-Merseburg and member of the House of Wettin.He was the eldest son of Christian II, Duke of Saxe-Merseburg, and Erdmuthe Dorothea of Saxe-Zeitz.
Knowledge 1: Sophie Charlotte of Württemberg
Sophie Charlotte of Württemberg (22 February 1671 – 11 September 1717), was a German noblewoman member of the House of Württemberg and by marriage Duchess of Saxe-Eisenach.Born in Stuttgart, she was the ninth of eleven children of Eberhard III, Duke of Württemberg and his second wife, Countess Marie Dorothea Sophie of Oettingen-Oettingen.From Sophie Charlotte's ten full-siblings, only she and his three (unmarried) brothers George Frederick, Louis and John Frederick survive adulthood; in addition, they had fourteen older half-siblings from their father's first marriage with Anna Katharina, Wild- and Rheingräfin of Salm-Kyrburg, of whom only eight survived:Sophie Louise (by marriage Margravine of Brandenburg-Bayreuth), Christine Fredericka (by marriage Duchess of Oettingen-Oettingen), Christine Charlotte (by marriage Princess of East Frisia), William Louis, Duke of Württemberg, Anna Katharine (unmarried), Eberhardine Katharine (by marriage Duchess of Oettingen-Oettingen), Frederick Charles, Duke of Württemberg-Winnental and Karl Maximilian (unmarried). [SEP] Knowledge 2: Albert IV, Duke of Saxe-Eisenach
Albrecht, Duke of Saxe-Eisenach, (Altenburg, 27 July 1599 – Eisenach, 20 December 1644) was a ruler of the duchy of Saxe-Eisenach.He was the seventh (but fourth surviving) son of Johann, Duke of Saxe-Weimar, and Dorothea Maria of Anhalt.His regnal name Albert IV derives from the numbering of the duchy of Saxony as a whole, not specifically to the succession in Saxe-Eisenach.Albrecht received his first instruction from the Field Marshal Frederick of Kospoth.Later he studied at the University of Jena with his brothers.In the years 1619-1621 he completed his "Cavalierstour" (Study Tour) with his younger brother Johann Frederick.The two princes travelled to France and Switzerland.After his return in 1621, Albrecht occupied himself with administrative duties until 1626.He also represented his absent brothers as regent.In Weimar on 24 June 1633 Albrecht married Dorothea of Saxe-Altenburg, daughter of Frederick William I, Duke of Saxe-Weimar.The marriage was childless.In accordance with a divisionary treaty concluded with his brothers, Albrecht received Eisenach in 1640.He died four years later, after which his state was merged with Saxe-Weimar under Wilhelm of Saxe-Weimar.

Answer: Eberhard III, Duke of Württemberg