Isabella of France, Dauphine of Viennois
" For other persons named Isabella of France, see Isabella of France( disambiguation)" Isabella of France and Burgundy( 1310 – April 1348) was the daughter of Philip V of France and Joan II, Countess of Burgundy.
Charles, Count of Valois
Charles of Valois (12 March 1270 – 16 December 1325), the third son of Philip III of France and Isabella of Aragon, was a member of the House of Capet and founder of the House of Valois, whose rule over France would start in 1328.
Charles ruled several principalities.
He held in appanage the counties of Valois, Alençon and Perche.
Through his marriage to Margaret of Anjou, he became Count of Anjou and Maine.
Through his marriage to Catherine I, titular empress of the Latin Empire, he was titular Latin Emperor of Constantinople from 1301–1307, although he ruled from exile and only had authority over Crusader States in Greece.
The grandson of Louis IX of France, Charles of Valois was a son, brother, brother-in-law and son-in-law of kings or queens (of France, Navarre, England and Naples).
His descendants, the House of Valois, would become the royal house of France three years after his death, beginning with his son Philip VI of France.
Bonne of Bourbon
Bonne of Bourbon( 1341 – 19 January 1402) was a daughter of Peter I, Duke of Bourbon, and Isabella of Valois, and hence a sister of Joanna of Bourbon.
She served as regent of Savoy during the absence of her spouse from 1366 to 1367, in 1383, and during the minority of her grandson Count Amadeus VIII in 1391.
Mathilde of Bourbon
Mathilde of Bourbon( – 18 June 1228) was a French noblewoman who was the ruling Lady of Bourbon from 1171 until her death.
Marie of Valois, Duchess of Calabria
Marie of Valois( 1309 – 23 October 1331), was the eldest daughter of Charles of Valois by his third wife Mahaut of Châtillon.
She was a member of the House of Valois.
One of her five children was Queen Joanna I of Naples.
Isabella of Valois, Duchess of Bourbon
Isabella of Valois, Duchess of Bourbon or "Isabella of France" (1313 – 26 July 1383), was a Petit Fille of France, and a daughter of Charles of Valois by his third wife Mahaut of Châtillon.
She was the wife of Peter I, Duke of Bourbon.
Beatrice of Bourbon, Queen of Bohemia
Beatrice of Bourbon( 1320 – 23 December 1383) was a French noblewoman.
A member of the House of Bourbon, she was by marriage Queen of Bohemia and Countess of Luxembourg.
She was the youngest daughter of Louis I, Duke of Bourbon, and Mary of Avesnes.
Blanche of Bourbon
Blanche of Bourbon( 1339 – 1361) was Queen of Castile as the wife of King Peter.
She was one of the daughters of Peter I, Duke of Bourbon and Isabella of Valois.
Bernard de Wisk
Bernard de Wisk was a mercenary captain and sometime brigand of the Hundred Years War.
Wisk started out a mercenary, However, after the Treaty of Brétigny was signed on May 8, 1360, Wisk found himself unemployed and so turned to Brigandry.
that ranged the French country side pillaging towns.
In 1369, with Bernardon and Hortingo de la Salle, he seized Belleperche Castle, home to Isabella of Valois, Duchess of Bourbon, mother- in- law of the king, Charles V of France and demanded a ransom.
The castle was, however, besieged by the troops of the Dukes of Bourbon and Burgundy.
The Duke of Bourbon( Louis II, Duke of Bourbon) was her son, and John Frossart tells us that the siege redoubt he organized was as strong and as well fortified as a good town might have been.
The" Free companies" in the castle were expelled, but they took the duchess with them as hostage.
The Duchess remained a prisoner until 1372, when the king arranged for the ransom to be paid.
Joan of Valois, Duchess of Alençon
Joan of Valois( 13 September 1409, in Blois – 19 May 1432, in Angers) was the only surviving child of Charles, Duke of Orléans, and Isabella of Valois.
She held the title Duchess of Alençon when married to John II of Alençon.

Question: Who is the paternal grandfather of Isabella Of Valois, Duchess Of Bourbon?
Answer: Philip III of France