Herbert IV, Count of Vermandois
Herbert IV of Vermandois( 1028–1080), Count of Vermandois, was the son of Otto of Vermandois and Parvie( Pavia or Patia).
Pepin III, Count of Vermandois
Pepin III, Count of Vermandois( also known as Pepin II, Count of Senlis; French:" Pépin")( c. 846 – 893) was a Frankish noble; the Count of Senlis and Count of Vermandois( 850 – 893); Lord of Valois( 877 – 886), and later Count of Valois( 886 – 893).
He was a son of Pepin, Count of Vermandois and Valois and thus a grandson of Bernard of Italy, who was himself a grandson of Charlemagne.
The brothers of Pepin III were Herbert I, Count of Vermandois and Bernard II, Count of Laon.
Pepin III of Vermandois's wife is unknown; their son was:
Gerberge of Lorraine
Gerberge of Lorraine (ca.
935-978) was the daughter of Giselbert, Duke of Lorraine, and Gerberga of Saxony, daughter of
Henry I the Fowler, King of Germany.
She was a descendant of Charlemagne through both her parents.
Gerberge died sometime after 7 September 978.
In or before 954, she married
Adalbert I of Vermandois.
Their children were:
Bernard of Senlis
Bernard I( or II) of Senlis( c. 919 – c. 947) was a Frankish noble from herbertien dynasty, a branch of carolingian dynasty.
He was a descendant of Charlemagne and his son Pepin of Italy.
A cousin of Herbert I, Count of Vermandois.
Bernard was a grandson of Pepin III, Count of Senlis and Valois( 846–893).
There's conflicting views on whether Pepin( 876–922) or Bernard( c. 875 – 927) was the younger Bernard's father.
He was Count of Beauvais and Count of Senlis.
Both he and his cousin Herbert I, Count of Vermandois were influential nobles of the western northern part of the Frankish Kingdom.
It's believed that Robert I of Senlis( d. 1004) was his son.
Stephen I, Count of Troyes
Stephen I of Vermandois( died 1020) was the seventh Count of Meaux, in the Champagne region of modern -day France, after his father Herbert of Vermandois.
He died without issue.
The title of Count of Meaux passed to Odo II of Blois.
Adalbert I, Count of Vermandois
Adalbert I of Vermandois(" the Pious"), in 946 he succeeded his father as Count of Vermandois.
Herbert III, Count of Vermandois
Herbert III of Vermandois (953–1015), Count of Vermandois, was the son of Adalbert I of Vermandois and Gerberge of Lorraine.
Elisabeth, Countess of Vermandois
" Not to be confused with Elizabeth of Vermandois, Countess of Leicester" Elisabeth of Vermandois also known as Isabelle Mabile or Isabelle de Vermandois
( 1143 – Arras 28 March 1183) was ruling Countess of Vermandois from 1168 to 1182, and also Countess of Flanders by marriage to Philip I, Count of Flanders.
She was the eldest daughter of Ralph I, Count of Vermandois and his second spouse Petronilla of Aquitaine.
Otto, Count of Vermandois
Otto( or Eudes) of Vermandois( or Vermicelli)( 29 August 979 – 25 May 1045), Count of Vermandois, was the son of Herbert III, Count of Vermandois and Ermengarde of Bar-sur- Seine.
He succeeded his brother, Adalbert II as count of Vermandois in 1015.
Otto donated property to Notre- Dame de Homblières by charter.
Herbert III of Omois
Herbert III d' Omois, Herbert the old( or Herbert III of Vermandois, 910 – 980/985) was count of Omois from 943 to his death.
He was the son of Herbert II, Count of Vermandois and Adela of France, daughter of King Robert I of France.
In 943 after his father died, he succeeded as count of Omois" and received the fortress of Château- Thierry as well as the abbey of Saint- Médard, Soissons."
In 951, in his late years, he was married to Eadgifu of Wessex, daughter of Edward the Elder, King of England, and widow of Charles the Simple King of West Francia.
After his death, King Lothair divided his estates between his nephews, Eudes I, Count of Blois and Herbert IV, Count of Troyes and Meaux.

Question: Who is Herbert Iii, Count Of Vermandois's maternal grandmother?
Answer: Gerberga of Saxony