John I, Count of Soissons
John I (d. after 1115), son of William Busac, Count of Eu and Soissons, and Adelaide, Countess of Soissons.
Count of Soissons.
John became Count of Soissons after the death of his brother Renaud II in 1099.
John was involved with the Abbey of St. Jean des Vignes.
John married Aveline de Pierrefonds, daughter of Nivelon II, Seigneur de Pierrefonds.
John and Aveline had one child:
Upon the death of John, his son Renaud became the last of the Norman Counts of Soissons.
John IV, Count of Soissons
John IV (d. before May 1302), son of John III, Count of Soissons, and Marguerite of Montfort, daughter of Amaury VI, Count of Montfort.
Count of Soissons, inherited upon his father’s death in 1286.
John married Marguerite of Rumigny, daughter of Hugh II of Rumigny and his wife Philippa.
John and Marguerite had two children:
Upon John’s death in 1302, his son and namesake became count.
John V, Count of Soissons
John V (21 March 1281 – 1304), son of John IV, Count of Soissons, and his wife Marguerite of Rumigny.
Count of Soissons.
John inherited the countship of Soissons from his father in 1302.
Nothing is known about his brief rule of the county.
He never married and died with no heirs.
Upon his death, his brother Hugh became Count of Soissons.
Adelaide, Countess of Soissons
Adelaide( died 1105), was sovereign Countess of Soissons from 1057 until 1105.
She was the daughter of Renaud I, Count of Soissons, and his wife, whose name is unknown, widow of Hilduin III, Count of Montdidier..
Adelaide became ruler of the County of Soissons upon the death of her father and brother, Guy II, Count of Soissons, in 1057.
Adelaide married William Busac, Count of Eu, grandson of Richard I, Duke of Normandy.
Adelaide and William had five children: William Busac became Count of Soissons," de jure uxoris", upon their marriage.
Margaret, Countess of Soissons
Margaret (or Margaretha) of Soissons (died ca. 1350) was ruling Countess of Soissons in 1305-1344.
She was the only daughter of Hugh, Count of Soissons, and Johanna of Argies.
In 1306 she succeeded her father as Countess of Soissons.
Margaret was married to John of Beaumont, son of John II, Count of Holland.
Margaret and John had five children:
Upon their marriage, John became Count of Soissons, "jure uxoris".
Nocher II, Count of Soissons
Nocher II( d. 1019), Count of Bar- sur- Aube, Count of Soissons.
He was the son of Nocher I, Count of Bar-sur- Aube.
Nocher ’s brother Beraud( d. 1052) was Bishop of Soissons.
Nocher became Count of Soissons, jure uxoris, upon his marriage to Adelise, Countess of Soissons.
Nocher and Adelisa had three children: Nocher ’s son and namesake became Count of Bar-sur- Aube upon his death, and the countship of Soissons reverted to his wife.
His son Renaud would eventually become the Count of Soissons.
William Busac
William Busac( 1020- 1076), son of William I, Count of Eu, and his wife Lesceline.
Count of Eu, Count of Soissons," de jure uxoris".
William was given the nickname Busac by the medieval chronicler Robert of Torigni.
William appealed to King Henry
I of France, who gave him in marriage Adelaide, the heiress of the county of Soissons.
Adelaide was daughter of Renaud I, Count of Soissons, and Grand Master of the Hotel de France.
William then became Count of Soissons in right of his wife.
William and Adelaide had four children:
His son Renaud became Count of Soissons upon William ’s death, and he was succeeded by his brother John.
John III, Count of Soissons
John III (d. before 8 October 1286), son of John II, Count of Soissons, and Marie de Chimay.
Count of Soissons and Seigneur of Chimay.
John inherited the countship of Soissons upon his father’s death in 1272.
John married Marguerite de Montfort, daughter of Amaury, Count of Montfort, and his wife Beatrix de Viennois.
John and Marguerite had five children:
John was succeeded as Count of Soissons by his son and namesake upon the former’s death.
Guy II, Count of Soissons
Guy II( d. 1057), son of Renaud I, Count of Soissons, and his wife( name unknown), widow of Hilduin III, Count of Montdidier.
Count of Soissons.
Guy was identified as Count of Soissons in 1042 in a charter in which Gaunilo of Marmoutiers, the treasurer of St. Martin, denoted property.
Guy died with his father in 1057 at the siege of Soissons.
It is not known whether or not Guy was married and no children are recorded.
Upon his death, his sister Adelaide assumed the countship of Soissons.
Renaud III, Count of Soissons
Renaud III( d. 1141), son of John I, Count of Soissons, and Aveline de Pierrefonds.
Count of Soissons.
Little is known about Renaud other than he inherited the Count of Soissons from his father in 1115.
Upon Renaud's death in 1141, Ivo II de Nesle was chosen as his successor by the Bishop of Soisson, Joscelin de Vierzi.
Renaud married Bathilde, of an unknown family, in 1137.
No children are recorded.
Renaud was the last of the Norman counts of Soissons.

Question: Who is John V, Count Of Soissons's paternal grandfather?
Answer: John III, Count of Soissons