Charles Martel
Charles Martel (688 – 22 October 741) was a Frankish statesman and military leader who, as Duke and Prince of the Franks and Mayor of the Palace, was the "de facto" ruler of Francia from 718 until his death.
He was a son of the Frankish statesman Pepin of Herstal and Pepin's mistress, a noblewoman named Alpaida.
Charles successfully asserted his claims to power as successor to his father as the power behind the throne in Frankish politics.
Continuing and building on his father's work, he restored centralized government in Francia and began the series of military campaigns that re-established the Franks as the undisputed masters of all Gaul.
According to a near-contemporary source, the "Liber Historiae Francorum", Charles was "a warrior who was uncommonly  effective in battle".
Much attention has been paid to his success in defeating an Arab invasion in Aquitaine at the Battle of Tours.
Alongside his military endeavours, Charles has been traditionally credited with a seminal role in the development of the Frankish system of feudalism.
At the end of his reign, Charles divided Francia between his sons, Carloman and Pepin.
The latter became the first king of the Carolingian dynasty.
Charles' grandson, Charlemagne, extended the Frankish realms, and became the first emperor in the West since the fall of Rome.
Maria Thins
Maria Thins( c. 1593 – 27 December 1680) was the mother- in- law of Johannes Vermeer and a member of the Gouda Thins family.
Ebba Eriksdotter Vasa
Ebba Eriksdotter Vasa (circa 1491 – 21 November 1549) was a Swedish noblewoman.
She was the mother of Queen Margaret Leijonhufvud and the second cousin and mother-in-law of King Gustav Vasa.
Cornelia (mother of the Gracchi)
Cornelia( c. 190s – c. 115 BC) was the second daughter of Publius Cornelius Scipio Africanus, the hero of the Second Punic War, and Aemilia Paulla.
She is remembered as a prototypical example of a virtuous Roman woman.
She was the mother of the Gracchi brothers, and the mother- in- law of Scipio Aemilianus.
Vera Miletić
Vera Miletić (Serbian Cyrillic: Вера Милетић; 8 March 1920 – 7 September 1944) was a Serbian student and soldier.
She was notable for being the mother of Mira Marković, posthumously making her the mother-in-law of Serbian president Slobodan Milošević.
Swanachild
Swanachild (also "Swanahild" or "Serenahilt") was the second wife of Charles Martel, who brought her back from his first campaign in Bavaria in 725, along with her uncle Grimoald's wife, Biltrude.
Swanachild belonged to the clan of the Agilolfings though her parentage is not quite clear.
Her parents could be:
With Charles Martel
she had one child, Grifo.
After the death of Charles, she supported her son's failed attempt to gain a portion of his inheritance.
This she did with the support of her uncle Odilo of Bavaria.
Afterwards she was relegated to the position of abbess of Chelles.
Although later Carolingian historians cast her as a concubine, she was during her time the rightful wife of Charles.
The "Reichenau Codex" listed her as "Suanahil reginaQueen Swanachild."
Eldon Howard
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.
Marian Shields Robinson
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.
Priscilla Pointer
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.
Baroness Gösta von dem Bussche-Haddenhausen
Baroness Gösta von dem Bussche- Haddenhausen( 26 January 1902 – 13 June 1996) was the mother of Prince Claus of the Netherlands, who was the Prince Consort of Queen Beatrix of the Netherlands, thus making her the mother- in- law of the former Dutch Queen.
She is also the paternal grandmother of King Willem- Alexander of the Netherlands, who is the current Dutch King.

Question: Who is the mother-in-law of Swanachild?
Answer: Alpaida