Question: Who is Joan Of France, Duchess Of Brittany's maternal grandmother?

Knowledge 1: Joan of France, Duchess of Brittany
Joan of France (24 January 1391 – 27 September 1433) was Duchess of Brittany by marriage toJohn V. She was a daughter of Charles VI of France and Isabeau of Bavaria. [SEP] Knowledge 2: Isabeau of Bavaria
Isabeau of Bavaria (or Isabelle; also Elisabeth of Bavaria-Ingolstadt; c. 1370 – 24 September 1435) was queen of France between 1385 and 1422.She was born into the House of Wittelsbach as the eldest daughter of Duke Stephen III of Bavaria-Ingolstadt and Taddea Visconti of Milan.At age 15 or 16, Isabeau was sent to the young King Charles VI of France; the couple wed three days after their first meeting.Isabeau was honored in 1389 with a lavish coronation ceremony and entry into Paris.In 1392 Charles suffered the first attack of what was to become a lifelong and progressive mental illness, resulting in periodic withdrawal from government.The episodes occurred with increasing frequency, leaving a court both divided by political factions and steeped in social extravagances.A 1393 masque for one of Isabeau's ladies-in-waiting—an event later known as "Bal des Ardents"—ended in disaster with the King almost burning to death.Although the King demanded Isabeau's removal from his presence during his illness, he consistently allowed her to act on his behalf.In this way she became regent to the Dauphin of France (heir apparent), and sat on the regency council, allowing far more power than was usual for a medieval queen.Charles' illness created a power vacuum that eventually led to the Armagnac–Burgundian Civil War between supporters of his brother, Duke Louis I of Orléans, and the royal dukes of Burgundy.Isabeau shifted allegiances as she chose the most favorable paths for the heir to the throne.When she followed the Armagnacs, the Burgundians accused her of adultery with Louis of Orléans; when she sided with the Burgundians the Armagnacs removed her from Paris and she was imprisoned.In 1407 John the Fearless assassinated Orléans, sparking hostilities between the factions.The war ended soon after Isabeau's eldest son, Charles, had John the Fearless assassinated in 1419—an act that saw him disinherited.Isabeau attended the 1420 signing of the Treaty of Troyes, which decided that the English king should inherit the French crown after the death of her husband, Charles VI.She lived in English-occupied Paris until her death in 1435.Isabeau was popularly seen as a spendthrift and irresponsible philanderess.In the late 20th and early 21st centuries historians re-examined the extensive chronicles of her lifetime, concluding that many elements of her reputation were unearned and stemmed from factionalism and propaganda.
Knowledge 1: Isabeau of Bavaria
Isabeau of Bavaria (or Isabelle; also Elisabeth of Bavaria-Ingolstadt; c. 1370 – 24 September 1435) was queen of France between 1385 and 1422.She was born into the House of Wittelsbach as the eldest daughter of Duke Stephen III of Bavaria-Ingolstadt and Taddea Visconti of Milan.At age 15 or 16, Isabeau was sent to the young King Charles VI of France; the couple wed three days after their first meeting.Isabeau was honored in 1389 with a lavish coronation ceremony and entry into Paris.In 1392 Charles suffered the first attack of what was to become a lifelong and progressive mental illness, resulting in periodic withdrawal from government.The episodes occurred with increasing frequency, leaving a court both divided by political factions and steeped in social extravagances.A 1393 masque for one of Isabeau's ladies-in-waiting—an event later known as "Bal des Ardents"—ended in disaster with the King almost burning to death.Although the King demanded Isabeau's removal from his presence during his illness, he consistently allowed her to act on his behalf.In this way she became regent to the Dauphin of France (heir apparent), and sat on the regency council, allowing far more power than was usual for a medieval queen.Charles' illness created a power vacuum that eventually led to the Armagnac–Burgundian Civil War between supporters of his brother, Duke Louis I of Orléans, and the royal dukes of Burgundy.Isabeau shifted allegiances as she chose the most favorable paths for the heir to the throne.When she followed the Armagnacs, the Burgundians accused her of adultery with Louis of Orléans; when she sided with the Burgundians the Armagnacs removed her from Paris and she was imprisoned.In 1407 John the Fearless assassinated Orléans, sparking hostilities between the factions.The war ended soon after Isabeau's eldest son, Charles, had John the Fearless assassinated in 1419—an act that saw him disinherited.Isabeau attended the 1420 signing of the Treaty of Troyes, which decided that the English king should inherit the French crown after the death of her husband, Charles VI.She lived in English-occupied Paris until her death in 1435.Isabeau was popularly seen as a spendthrift and irresponsible philanderess.In the late 20th and early 21st centuries historians re-examined the extensive chronicles of her lifetime, concluding that many elements of her reputation were unearned and stemmed from factionalism and propaganda. [SEP] Knowledge 2: Joan Holland, Duchess of Brittany
Lady Joan Holland (1350 – October 1384) was Duchess of Brittany as the second wife of John IV, Duke of Brittany.She was the daughter of Joan of Kent and Thomas Holland, 1st Earl of Kent.Her mother married secondly to Edward the Black Prince and was mother to Richard II.Her marriage to John IV took place in London in May 1366, but without the approval of King Edward III of England, Joan's step-grandfather, who claimed overlordship of Brittany.The couple had no children.Joan's death, in her thirties, was politically inexpedient.In 1386, two years afterwards, John IV married Joan of Navarre, later the queen of King Henry VI of England.
Knowledge 1: Joan of France, Duchess of Brittany
Joan of France (24 January 1391 – 27 September 1433) was Duchess of Brittany by marriage toJohn V. She was a daughter of Charles VI of France and Isabeau of Bavaria. [SEP] Knowledge 2: Joan Holland, Duchess of Brittany
Lady Joan Holland (1350 – October 1384) was Duchess of Brittany as the second wife of John IV, Duke of Brittany.She was the daughter of Joan of Kent and Thomas Holland, 1st Earl of Kent.Her mother married secondly to Edward the Black Prince and was mother to Richard II.Her marriage to John IV took place in London in May 1366, but without the approval of King Edward III of England, Joan's step-grandfather, who claimed overlordship of Brittany.The couple had no children.Joan's death, in her thirties, was politically inexpedient.In 1386, two years afterwards, John IV married Joan of Navarre, later the queen of King Henry VI of England.

Answer: Taddea Visconti