Question: Who is the mother-in-law of Blanche Of Navarre, Duchess Of Brittany?

Context paragraphs:
title: John I, Duke of Brittany
paragraph_text: John I (c. 1217/188 October 1286), known as John the Red due to the colour of his beard, was Duke of Brittany from 1221 to his death and 2nd Earl of Richmond in 1268. John was the eldest of three children born to Duchess Alix and her husband and "jure uxoris" co-ruler, Duke Peter I. He became duke upon his mother's death in 1221. His father, who had reigned as duke due to his marriage to Alix, ruled as regent until John reached adulthood. In 1268, Henry III granted the earldom of Richmond to John, and the title continued in his family, through frequent temporary forfeitures and reversions, until 1342. He experienced a number of conflicts with the Bishop of Nantes and the Breton clergy. In 1240, he issued an edict expelling Jews from the duchy and cancelling all debts to them. He joined Louis IX of France in the Eighth Crusade in 1270, and survived the plague that killed the king. The duchy of Brittany experienced a century of peace, beginning with John I and ending with Duke John III's reign in 1341.
title: Priscilla Pointer
paragraph_text: Priscilla Marie Pointer( born May 18, 1924) is an American stage, film and television character actress. She began her career in the theater, including productions on Broadway. Later, Pointer moved to Hollywood to act in films and on television. She is the mother of Amy Irving, therefore making her the former mother- in- law of filmmakers Steven Spielberg and Bruno Barreto and the mother- in- law of documentary filmmaker Kenneth Bowser, Jr.
title: Blanche of Navarre, Countess of Champagne
paragraph_text: Blanche of Navarre( ?–1229) was countess and then regent of Champagne and finally also regent of her native kingdom of Navarre. She was the youngest daughter of Sancho VI of Navarre and Sancha of Castile, who died in 1179, about two years after Blanche's birth. Her eldest brother, Sancho VII of Navarre, succeeded their father as King of Navarre and was the last male descendant of the first dynasty of Kings of Navarre, the Pamplona dynasty, dying childless. Her elder sister Berengaria of Navarre married Richard I of England.
title: Maria Thins
paragraph_text: Maria Thins( c. 1593 – 27 December 1680) was the mother- in- law of Johannes Vermeer and a member of the Gouda Thins family.
title: Blanche II of Navarre
paragraph_text: Blanche II( 9 June 1424 – 2 December 1464), titular queen of Navarre, was the daughter of John II of Aragon and Blanche I of Navarre. She was also Princess of Asturias by marriage.
title: Eldon Howard
paragraph_text: Eldon Howard was a British screenwriter. She was the mother- in- law of Edward J. Danziger and wrote a number of the screenplays for films by his company Danziger Productions.
title: Marian Shields Robinson
paragraph_text: Marian Lois Robinson( née Shields; born July 29, 1937) is the mother of Michelle Obama, former First Lady of the United States, and Craig Robinson, a basketball executive, and the mother- in- law of former U.S. President Barack Obama.
title: Blanche of Navarre, Duchess of Brittany
paragraph_text: Blanche of Navarre( 1226 – 12 August 1283), also known as Blanche of Champagne, was the daughter of Theobald the Troubador, King of Navarre and Count of Champagne, and his second wife Agnes of Beaujeu. She was a member of the House of Champagne. By her marriage to John I, Duke of Brittany, she became Duchess consort of Brittany.
title: Isabella of Navarre, Viscountess of Rohan
paragraph_text: Isabel d' Albret of Navarre( 1512–1555) was the daughter of John III of Navarre( died 1516) and Catherine I of Navarre, sister and heiress of Francis Phoebus, King of Navarre. As heir apparent, her brother rose to the throne in 1517 as Henry II of Navarre, grandfather of King Henry III of Navarre( Henry IV of France).
title: Charles, Prince of Viana
paragraph_text: Charles, Prince of Viana( 29 May 1421 – 23 September 1461), sometimes called Charles IV of Navarre, was the son of King John II of Aragon and Queen Blanche I of Navarre.

Reasoning steps:
Blanche of Navarre spouse John I, Duke of Brittany
John I, Duke of Brittany mother Alix

Answer: spans: Alix
Duchess Alix