Peter, Hereditary Prince of Yugoslavia
Peter, Hereditary Prince of Yugoslavia( born 5 February 1980), also known as Peter III Karađorđević(/" Petar III Karađorđević"), is the eldest son of Alexander, Crown Prince of Yugoslavia, and Princess Maria da Gloria of Orléans- Braganza.
Prince Peter is the grandson of King Peter II.
Peter, Hereditary Prince of Yugoslavia' is second in line after his father HRH Crown Prince Alexander to the defunct throne.
Princess Tatiana of Sayn-Wittgenstein-Berleburg
Princess Tatiana of Sayn-Wittgenstein-Berleburg (Tatiana Louise Ursula Therese Elsa; born 31 July 1940) is the fourth child and second daughter of Gustav Albrecht, 5th Prince of Sayn-Wittgenstein-Berleburg, and his wife, Margareta Fouché d'Otrante, and younger sister of Prince Richard of Sayn-Wittgenstein-Berleburg, the husband of Princess Benedikte of Denmark.
Tatjana is the former wife of the late Moritz, Landgrave of Hesse, from 1980 head of the House of Hesse.
Their marriage took place in the summer of 1964 in Gießen.
They divorced in 1974.
Princess Elisabeth of Hesse-Kassel
Princess Charlotte" Elizabeth" Alexandra Mary Louise of Hesse- Kassel( 13 June 1861 – 7 June 1955), was a Princess of Hesse- Kassel by birth and, by her marriage to Leopold, Hereditary Prince of Anhalt, the Hereditary Princess of Anhalt.
Princess Luise Dorothea of Prussia
Princess Luise Dorothea of Prussia( Luise Dorothea Sophie; 29 September 1680 – 23 December 1705) was Hereditary Princess of Hesse- Kassel by marriage to Frederick, Hereditary Prince of Hesse- Kassel.
She was the daughter of Frederick I, First King in Prussia by his first wife Elisabeth Henriette of Hesse- Kassel.
She died in childbirth.
Donatus, Landgrave of Hesse
Donatus, Prince and Landgrave of Hesse ("Heinrich Donatus Philipp Umberto"; born 17 October 1966) is the eldest son and successor of German aristocrat Moritz, Landgrave of Hesse, and his former wife, Princess Tatiana of Sayn-Wittgenstein-Berleburg.
A great-grandson of Victor Emmanuel III of Italy
, he is named in part after Georg Donatus, Hereditary Grand Duke of Hesse.
He is also a great-great-great grandson of Queen Victoria of the United Kingdom, through his paternal grandfather Philipp's mother Margaret, a granddaughter of Queen Victoria.
His father Moritz was a third cousin of Queen Elizabeth II of the United Kingdom.
Heinrich Donatus, Hereditary Prince of Schaumburg-Lippe
Heinrich Donatus, Hereditary Prince of Schaumburg- Lippe( Ernst- August Alexander Wilhelm Bernhard Krafft Heinrich Donatus; born 13 May 1994) is the son of Alexander, Prince of Schaumburg- Lippe and thus heir to the German Princely house of Schaumburg- Lippe.
Prince Heinrich Donatus of Schaumburg- Lippe was born in Hanover to Alexander, Hereditary Prince of Schaumburg- Lippe( born 1958), and Princess Marie- Louise(" Lilly") of Sayn- Wittgenstein- Berleburg( born 1972), who had married in August 1993.
His mother suffered a nervous breakdown in 1998, and left her husband in 2000 to move with her son from Hanover to Munich.
The couple divorced in 2002.
On the death of his father, Philip- Ernst, Prince of Schaumburg- Lippe, Alexander inherited the title Prince of Schaumburg- Lippe, while his son became Hereditary Prince.
In 2007, the Prince of Schaumburg- Lippe married lawyer Nadja Anna Zsoeks.
Princess Marie- Louise is now married to designer Lambros Milona, with whom she has a daughter, Lana.
Prince George Bernhard of Anhalt-Dessau
George Bernhard of Anhalt- Dessau( 21 February 1796 – 16 October 1865), was a German prince of the House of Ascania from the Anhalt- Dessau branch.
He was born in Dessau, the second son of Frederick, Hereditary Prince of Anhalt- Dessau, by his wife Landgravine Amalie of Hesse- Homburg, daughter of Frederick V, Landgrave of Hesse- Homburg.
Princess Wilhelmine of Baden
Princess Wilhelmine of Baden( 21 September 1788 – 27 January 1836), was by birth Princess of Baden and by marriage Grand Duchess consort of Hesse and the Rhine.
She was the youngest daughter of Charles Louis, Hereditary Prince of Baden and Amalie of Hesse- Darmstadt.
Carol Victor, Hereditary Prince of Albania
Carol Victor, Hereditary Prince of Albania( Karl Viktor Wilhelm Friedrich Ernst Günther von Wied, 19 May 19138 December 1973) was the only son of William, Prince of Albania and briefly heir to the Principality of Albania.
He held the title of" Hereditary Prince of Albania".
He was also styled Skënder, in homage to Skanderbeg, the national hero.
Joseph, Hereditary Prince of Hesse-Rotenburg
Joseph of Hesse- Rotenburg( 23 September 1705 – 24 June 1744) was the Hereditary Prince of Hesse- Rotenburg from his birth till his death in 1744.
He was heir apparent to the Landgraviate of Hesse- Rotenburg.

Question: Who is the maternal grandfather of Donatus, Landgrave Of Hesse?