Question: Who is the father-in-law of Ermengarde Of Hesbaye?

Knowledge 1: Ermengarde of Hesbaye
Ermengarde (or Irmingard) of Hesbaye (c. 778 – 3 October 818), probably a member of the Robertian dynasty, was Carolingian empress from 813 and Queen of the Franks from 814 until her death as the wife of the Carolingian emperor Louis the Pious. [SEP] Knowledge 2: Louis the Pious
Louisthe Pious (778 – 20 June 840), also called the Fair, and the Debonaire, was the King of the Franks and co-emperor with his father, Charlemagne, from 813.He was also King of Aquitaine from 781.As the only surviving adult son of Charlemagne and Hildegard, he became the sole ruler of the Franks after his father's death in 814, a position which he held until his death, save for the period 833–34, during which he was deposed.During his reign in Aquitaine, Louis was charged with the defence of the empire's southwestern frontier.He conquered Barcelona from the Muslims in 801 and asserted Frankish authority over Pamplona and the Basques south of the Pyrenees in 812.As emperor he included his adult sons, Lothair, Pepin, and Louis, in the government and sought to establish a suitable division of the realm among them.The first decade of his reign was characterised by several tragedies and embarrassments, notably the brutal treatment of his nephew Bernard of Italy, for which Louis atoned in a public act of self-debasement.In the 830shis empire was torn by civil war between his sons, only exacerbated by Louis's attempts to include his son Charles by his second wife in the succession plans.Though his reign ended on a high note, with order largely restored to his empire, it was followed by three years of civil war.Louis is generally compared unfavourably to his father, though the problems he faced were of a distinctly different sort.
Knowledge 1: Louis the Pious
Louisthe Pious (778 – 20 June 840), also called the Fair, and the Debonaire, was the King of the Franks and co-emperor with his father, Charlemagne, from 813.He was also King of Aquitaine from 781.As the only surviving adult son of Charlemagne and Hildegard, he became the sole ruler of the Franks after his father's death in 814, a position which he held until his death, save for the period 833–34, during which he was deposed.During his reign in Aquitaine, Louis was charged with the defence of the empire's southwestern frontier.He conquered Barcelona from the Muslims in 801 and asserted Frankish authority over Pamplona and the Basques south of the Pyrenees in 812.As emperor he included his adult sons, Lothair, Pepin, and Louis, in the government and sought to establish a suitable division of the realm among them.The first decade of his reign was characterised by several tragedies and embarrassments, notably the brutal treatment of his nephew Bernard of Italy, for which Louis atoned in a public act of self-debasement.In the 830shis empire was torn by civil war between his sons, only exacerbated by Louis's attempts to include his son Charles by his second wife in the succession plans.Though his reign ended on a high note, with order largely restored to his empire, it was followed by three years of civil war.Louis is generally compared unfavourably to his father, though the problems he faced were of a distinctly different sort. [SEP] Knowledge 2: Thuringbert, Count of Hesbaye
Thuringbert (735–770), Count of Hesbaye and Count of Wormsgau, son of Robert I, Count of Hesbaye, and Williswinda.
Thuringbert and his wife (name unknown) had one child:Thuringbert was succeeded as Count of Hesbaye by his son Robert.
Knowledge 1: Louis the Pious
Louisthe Pious (778 – 20 June 840), also called the Fair, and the Debonaire, was the King of the Franks and co-emperor with his father, Charlemagne, from 813.He was also King of Aquitaine from 781.As the only surviving adult son of Charlemagne and Hildegard, he became the sole ruler of the Franks after his father's death in 814, a position which he held until his death, save for the period 833–34, during which he was deposed.During his reign in Aquitaine, Louis was charged with the defence of the empire's southwestern frontier.He conquered Barcelona from the Muslims in 801 and asserted Frankish authority over Pamplona and the Basques south of the Pyrenees in 812.As emperor he included his adult sons, Lothair, Pepin, and Louis, in the government and sought to establish a suitable division of the realm among them.The first decade of his reign was characterised by several tragedies and embarrassments, notably the brutal treatment of his nephew Bernard of Italy, for which Louis atoned in a public act of self-debasement.In the 830shis empire was torn by civil war between his sons, only exacerbated by Louis's attempts to include his son Charles by his second wife in the succession plans.Though his reign ended on a high note, with order largely restored to his empire, it was followed by three years of civil war.Louis is generally compared unfavourably to his father, though the problems he faced were of a distinctly different sort. [SEP] Knowledge 2: Sigramnus, Count of Hesbaye
Sigramnus (Sigrand), was the Count of Hesbaye.Sigramnus became Count of Hesbaye by virtue of his marriage to the daughter of Lambert, Count of Hesbaye.The dates of his rule are unknown but are believed to be between that of Lambert’s son and grandson, and so it was perhaps an interim position until the latter became of age.The only knowledge available on Sigramnus is through his son, the Bishop of Metz, and grandson Ingerman of Hesbaye, father of Ermengard, wife of Louis the Pious.Sigramnus is known to have been an early supporter of Charles Martel, even before the Battle of Amblève.Sigramnus married , daughter of Lambert, Count of Hesbaye.They had three children:
Previous histories have portrayed Sigramnus as the husband of the daughter of Charles Martel, but this has been largely discredited.Sigramnus was succeeded by his nephew Cancor as Count of Hesbaye.

Answer: Charlemagne