Isabella of Bourbon
Isabella of Bourbon, Countess of Charolais( 1434 – 25 September 1465) was the second wife of Charles the Bold, Count of Charolais and future Duke of Burgundy.
She was a daughter of Charles I, Duke of Bourbon and Agnes of Burgundy, and the mother of Mary of Burgundy, heiress of Burgundy.
Otto-William, Count of Burgundy
Otto- William( 955/62 – 21 September 1026 AD), was Count of Mâcon, Count of Nevers, and the Count of Burgundy.
Ermentrude de Roucy
Ermentrude de Roucy (born 958 - died 5 May 1005)
(Irmtrude) was a Countess and Duchess of Burgundy.
She was a daughter of Renaud of Roucy and his wife, Alberade of Lorraine, daughter of Gilbert, Duke of Lorraine.
Ermentrude married Alberic II of Mâcon and thus became a countess of Mâcon.
She also married Otto-William, Count of Burgundy.
They had children:
Sibylla of Burgundy, Duchess of Burgundy
Sybilla of Burgundy( 1065 – 1103), was a French noble, Duchess consort of Burgundy by marriage to Eudes I, Duke of Burgundy.
She was a daughter of William I, Count of Burgundy and Stephanie.
She was married to Eudes I, Duke of Burgundy in 1080.
Children:
Reginald I, Count of Burgundy
Reginald I, Count of Burgundy
(aka Renaud I, Count Palatine of Burgundy) was the second Count of the Free County of Burgundy.
Born in 986, he was the son of Otto-William, Count of Burgundy (the first Count) and Ermentrude de Roucy.
In 1016, Reginald married Alice of Normandy.
He succeeded to the County on his father's death in 1026.
Reginald was succeeded by his son, William I, on his death in 1057.
Reginald married Alice and had the following children:
Florine of Burgundy
Florine of Burgundy( 1083–1097) was a French crusader.
She was the daughter of Eudes I, Duke of Burgundy and Sybilla of Burgundy.
Her maternal grandfather was William I, Count of Burgundy.
Florine was married to Sweyn the Crusader, a son of Sweyn II of Denmark.
Alberic III of Dammartin
Alberic III of Dammartin( Aubry de Dammartin)( – 19 September 1200) was a French count and son of Alberic II, Count of Dammartin, and Clémence de Bar, daughter of Reginald I, Count of Bar.
He married Mathilde, heiress to the county of Clermont and daughter of Renaud II, Count of Clermont.
They had:
Joan III, Countess of Burgundy
Joan III of Burgundy( 1/2 May 1308 – 10/15 August 1347), also known as Joan of France was a reigning Countess of Burgundy and Artois in 1330 – 1349, She was also Duchess of Burgundy by marriage to Odo IV, Duke of Burgundy.
She was the eldest daughter of King Philip V of France and Countess Joan II of Burgundy.
Alice of Normandy
Alice or Adeliza, Adelaide or Aelis( c. 1002 – 1038) was a countess consort of Burgundy, the daughter of Richard II, Duke of Normandy( 972–1026) and Judith of Brittany.
She married Reginald I, Count of Burgundy and had the following children:
Robert, Count of Burgundy
Robert, Count of Burgundy( 1300 – 1315) was the son of Otto IV, Count of Burgundy and Mahaut, Countess of Artois.
He was count of Burgundy between 1302 and 1315.
He died in 1315, and was succeeded by his sister, Joan II, and brother- in- law, Philip II, later queen and king of France.

Question: Who is Reginald I, Count Of Burgundy's maternal grandfather?
Answer: Renaud of Roucy