Question: Who is the maternal grandfather of Princess Adelaide Of Schleswig-Holstein-Sonderburg-Glücksburg?

Karl, Duke of Schleswig-Holstein-Sonderburg-Glücksburg
Karl of Schleswig -Holstein- Sonderburg- Glücksburg( 30 September 1813 at Gottorp in Schleswig, Duchy of Schleswig – 24 October 1878 at Luisenlund, Glücksburg, in Schleswig- Holstein, Prussia) was the second Duke of Schleswig- Holstein- Sonderburg- Glücksburg.
Karl was the eldest son of Friedrich Wilhelm, Duke of Schleswig- Holstein- Sonderburg- Glücksburg and Princess Louise Caroline of Hesse- Kassel and an elder brother of Christian IX of Denmark.
Karl became Duke of Schleswig- Holstein- Sonderburg- Glücksburg upon his father's death on 27 February 1831.
Friedrich, Duke of Schleswig-Holstein-Sonderburg-Glücksburg
Friedrich of Schleswig- Holstein- Sonderburg- Glücksburg( 23 October 1814 in Schleswig, Duchy of Schleswig – 27 November 1885 in Luisenlund, Schleswig- Holstein, Prussia) was the third Duke of Schleswig- Holstein- Sonderburg- Glücksburg.
Friedrich was the second- eldest son of Friedrich Wilhelm, Duke of Schleswig- Holstein- Sonderburg- Glücksburg and Princess Louise Caroline of Hesse- Kassel and an elder brother of Christian IX of Denmark.
Friedrich inherited the title of Duke of Schleswig- Holstein- Sonderburg- Glücksburg upon his childless brother Karl's death on 14 October 1878.
Prince Albert of Schleswig-Holstein-Sonderburg-Glücksburg
Prince Albert of Schleswig- Holstein- Sonderburg- Glücksburg( 15 March 1863, Kiel, Duchy of Holstein – 23 April 1948, Glücksburg, Schleswig- Holstein, Germany) was the fifth and youngest child of Friedrich, Duke of Schleswig- Holstein- Sonderburg- Glücksburg and his wife Princess Adelheid of Schaumburg- Lippe and was a nephew of Christian IX of Denmark.
Albert was the grandfather of Ernst August, Prince of Hanover through his daughter Princess Ortrud of Schleswig- Holstein- Sonderburg- Glücksburg.
Albert was recognized by a family compact of 1904 as possessing rights of succession to the Grand Duchy of Oldenburg in the event of the extinction of the reigning Grand Ducal line.
Princess Karoline Mathilde of Schleswig-Holstein-Sonderburg-Augustenburg
Princess Karoline Mathilde of Schleswig-Holstein-Sonderburg-Augustenburg (25 January 1860, in Augustenborg, Jutland, Denmark – 20 February 1932, in Grünholz, Province of Schleswig-Holstein, Free State of Prussia, Weimar Republic) was the second-eldest daughter of Frederick VIII, Duke of Schleswig-Holstein and his wife Princess Adelheid of Hohenlohe-Langenburg.
Friedrich Wilhelm, Duke of Schleswig-Holstein-Sonderburg-Glücksburg
Friedrich Wilhelm, Duke of Schleswig-Holstein-Sonderburg-Glücksburg (4 January 1785 – 17 February 1831) inherited the title of Duke of Schleswig-Holstein-Sonderburg-Beck in 1816.
He subsequently changed his title to Duke of Schleswig-Holstein-Sonderburg-Glücksburg in 1825 and founded a line that includes the Royal Houses of Denmark, Greece, Norway, and the Commonwealth realms.
Princess Helena Adelaide of Schleswig-Holstein-Sonderburg-Glücksburg
Princess Helena Adelaide of Schleswig-Holstein- Sonderburg- Glücksburg( 1 June 1888- 30 June 1962) was the third eldest daughter of Friedrich Ferdinand, Duke of Schleswig- Holstein and his wife Princess Karoline Mathilde of Schleswig- Holstein- Sonderburg- Augustenburg.
She was a princess of Denmark through her marriage within the House of Schleswig- Holstein- Sonderburg- Glücksburg to Prince Harald of Denmark.
Princess Helena was a Nazi sympathiser during World War II and was after the war exiled from Denmark, but eventually allowed to return, where she died.
Princess Karoline Mathilde of Schleswig-Holstein-Sonderburg-Glücksburg
Princess Karoline Mathilde of Schleswig- Holstein- Sonderburg- Glücksburg( Viktoria- Irene Adelheid Auguste Alberta Feodora Karoline Mathilde of Schleswig -Holstein- Sonderburg- Glücksburg; 11 May 1894 – 28 January 1972) was a member of the House of Schleswig- Holstein- Sonderburg- Glücksburg and Princess of Schleswig- Holstein- Sonderburg- Glücksburg by birth and a member of the House of Solms Baruth and Countess of Solms Baruth through her marriage to Count Hans of Solms- Baruth.
Princess Adelaide of Schleswig-Holstein-Sonderburg-Glücksburg
Princess "Adelaide" Louise of Schleswig-Holstein-Sonderburg-Glücksburg (19 October 1889 – 11 June 1964) was a daughter of Friedrich Ferdinand, Duke of Schleswig-Holstein and his wife Princess Karoline Mathilde of Schleswig-Holstein-Sonderburg-Augustenburg.
Princess Adelaide was the Princess consort of Solms-Baruth through her marriage to Friedrich, 3rd Prince of Solms-Baruth.
Augusta of Schleswig-Holstein-Sonderburg-Glücksburg
Princess Augusta of Schleswig-Holstein- Sonderburg- Glücksburg( 27 June 1633 – 26 May 1701) was a Danish- German princess of the senior Glücksburg line of the Duke of Schleswig- Holstein.
She was the first Duchess of Augustenborg by marriage.
Augustenborg palace, and as a consequence the nearby town, were named in honor of her.
The great- granddaughter of king Christian III of Denmark, she was the third daughter, eighth by birth, of Philip, Duke of Schleswig- Holstein- Sonderburg- Glücksburg and Princess Sophia Hedwig of Saxe- Lauenburg.
She was sister of Sophia Dorothea of Schleswig- Holstein- Sonderburg- Glücksburg
Friedrich Ferdinand, Duke of Schleswig-Holstein
Friedrich Ferdinand of Schleswig- Holstein- Sonderburg- Glücksburg( 12 October 1855 – 21 January 1934) was the fourth Duke of Schleswig- Holstein- Sonderburg- Glücksburg and became Duke of Schleswig- Holstein in 1931.

Answer: Frederick VIII, Duke of Schleswig-Holstein