Prince Edward, Duke of York and Albany
Prince Edward, Duke of York and Albany,( Edward Augustus; 25 March 1739 – 17 September 1767) was the younger brother of George III of the United Kingdom and the second son of Frederick, Prince of Wales, and Princess Augusta of Saxe- Gotha.
Princess Augusta of Saxe-Gotha
Princess Augusta of Saxe-Gotha-Altenburg (– 8 February 1772) was Princess of Wales by marriage to Frederick, Prince of Wales.
She was one of only four Princesses of Wales who never became queen consort, as her eldest son succeeded her father-in-law as George III of the United Kingdom in 1760 rather than her spouse, who had died nine years earlier.
Augusta was presumptive regent of Great Britain in the event of a regency between the death of her spouse in 1751, until the majority of her son in 1756, though in the event her father-in-law, George II, lived until 1760.
Dorothea Maria of Saxe-Gotha-Altenburg
Dorothea Maria of Saxe- Gotha-Altenburg( 12 February 1654 in Gotha – 17 June 1682 in Gotha), was a German princess member of the House of Wettin in the Ernestine branch of Saxe- Gotha- Altenburg.
She was the twelfth child and fourth daughter of Ernest I, Duke of Saxe- Gotha by his wife Elisabeth Sophie, the only daughter of John Philip, Duke of Saxe- Altenburg.
Fredericka of Saxe-Gotha-Altenburg
Fredericka of Saxe- Gotha-Altenburg( 17 July 1715 – 2 May 1775), was a German noblewoman member of the House of Wettin and by marriage Duchess of Saxe- Weissenfels.
Born in Gotha, she was the fifteenth of nineteen children born from the marriage of Frederick II, Duke of Saxe- Gotha- Altenburg and Magdalena Augusta of Anhalt- Zerbst.
From her eighteen older and younger siblings, only eight survived to adulthood: Frederick III, Duke of Saxe- Gotha- Altenburg, William, John August, Christian William, Louis Ernest, Maurice, Augusta( by marriage Princess of Wales), and John Adolph.
Frederick III, Duke of Saxe-Gotha-Altenburg
Frederick III, Duke of Saxe- Gotha-Altenburg( 14 April 1699 – 10 March 1772), was a duke of Saxe- Gotha- Altenburg.
Ernest II, Duke of Saxe-Gotha-Altenburg
Ernest II, Duke of Saxe-Gotha-Altenburg (Gotha, 30 January 1745 – Gotha, 20 April 1804) was the reigning Duke of Saxe-Gotha-Altenburg from 1772 to 1804.
He was the third but second surviving son of Frederick III, Duke of Saxe-Gotha-Altenburg and Luise Dorothea of Saxe-Meiningen.
The death of his older brother Frederick in 1756 made him the heir to the duchy of Saxe-Gotha-Altenburg.
Frederick, Prince of Wales
Frederick, Prince of Wales, KG (Frederick Louis; 1 February 170731 March 1751), was heir apparent to the British throne from 1727 until his death from a lung injury at the age of 44.
He was the eldest but estranged son of King George II and Caroline of Ansbach, and the father of King George III.
Under the Act of Settlement passed by the English Parliament in 1701, Frederick was fourth in the line of succession to the British throne at birth, after his great-grandmother, paternal grandfather and father.
He moved to Great Britain following the accession of his father, and was created Prince of Wales.
He predeceased his father, however, and upon the latter's death on 25 October 1760, the throne passed to Prince Frederick's eldest son, George III.
Frederick IV, Duke of Saxe-Gotha-Altenburg
Frederick IV, Duke of Saxe-Gotha-Altenburg (Gotha, 28 November 1774 – Gotha, 11 February 1825), was the last duke of Saxe-Gotha-Altenburg.
He was the third but second surviving son of Ernst II, Duke of Saxe-Gotha-Altenburg and Charlotte de Saxe-Meiningen.
After the death of his older brother August without sons (1822), Frederick (the only surviving male of the house) inherited the duchy of Saxe-Gotha-Altenburg.
Frederick fought - after military training - in the Napoleonic campaigns and was heavily wounded.
As a consequence of these injuries, he was constantly ill until his death.
Because of his illness, he traveled for a long time seeking a cure.
During these stays outside of his duchy, he left the government in hands of his secret advisor Bernhard August von Lindenau.
He only reigned three years and died unmarried; with him, the line of Saxe-Gotha-Altenburg ended.
After his death, his lands were repartitioned among his Wettin relations.
Ernst I of Saxe-Coburg-Saalfeld received Gotha, and changed his title to "Duke of Saxe-Coburg and Gotha", although the two duchies remained technically separate in a personal union.
Altenburg was thereafter ruled by the Duke of Saxe-Hildburghausen, whose dukedom was transferred to Saxe-Meiningen along with Saxe-Saalfeld, which Saxe-Coburg gave up in return for receiving Saxe-Gotha.
Prince John August of Saxe-Gotha-Altenburg
Johann August of Saxe- Gotha-Altenburg( 17 February 1704 – 8 May 1767), was a German prince, member of the House of Saxe- Gotha- Altenburg.
He was born in Gotha, the fifth but second surviving son of Frederick II, Duke of Saxe- Gotha- Altenburg and Magdalene Augusta of Anhalt- Zerbst.
Princess Charlotte of Saxe-Meiningen
Princess Charlotte of Saxe- Meiningen( 11 September 1751, Frankfurt am Main, Free Imperial City of Frankfurt, Holy Roman Empire – 25 April 1827, Genoa, Kingdom of Sardinia) was a member of the House of Saxe- Meiningen and a Princess of Saxe- Meiningen by birth and a member of the House of Saxe- Gotha- Altenburg and Duchess consort of Saxe- Gotha- Altenburg through her marriage to Ernest II, Duke of Saxe- Gotha- Altenburg.

Question: Who is Princess Augusta Of Saxe-Gotha's mother-in-law?
Answer: Caroline of Ansbach