Question: Who is Agnes Of Austria (1281–1364)'s father-in-law?

Context paragraphs:
title: Agnes of Austria (1281–1364)
paragraph_text: Agnes of Austria( 18 May 1281 – 10 June 1364) was a Queen consort of Hungary by marriage to Andrew III of Hungary.
title: Andrew III of Hungary
paragraph_text: Andrew III the Venetian( 126514 January 1301) was King of Hungary and Croatia between 1290 and 1301. His father, Stephen the Posthumous, was the posthumous son of Andrew II of Hungary although Stephen's brothers considered him a bastard. Andrew grew up in Venice, and first arrived in Hungary upon the invitation of a rebellious baron, Ivan Kőszegi, in 1278. Kőszegi tried to play Andrew off against Ladislaus IV of Hungary, but the conspiracy collapsed and Andrew returned to Venice. Being the last male member of the House of Árpád, Andrew was elected king after the death of King Ladislaus IV in 1290. He was the first Hungarian monarch to issue a coronation diploma confirming the privileges of the noblemen and the clergy. At least three pretenders — Albert of Austria, Mary of Hungary, and an adventurer — challenged his claim to the throne. Andrew expelled the adventurer from Hungary and forced Albert of Austria to conclude a peace within a year, but Mary of Hungary and her descendants did not renounce their claim. The Hungarian bishops and Andrew's maternal family from Venice were his principal supporters, but the leading Croatian and Slavonian lords were opposed to his rule. Hungary was in a state of constant anarchy during Andrew's reign. The Kőszegis, the Csáks, and other powerful families autonomously governed their domains, rising up nearly every year in open rebellion against Andrew. With Andrew's death, the House of Árpád became extinct. A civil war ensued which lasted for more than two decades and ended with the victory of Mary of Hungary's grandson, Charles Robert.
title: James Armour (Master mason)
paragraph_text: James Armour (15 January 1730 – 20 September 1798) was a master mason and father of Jean Armour, and therefore the father-in-law of the poet Robert Burns.
title: Agnes of Waiblingen
paragraph_text: Agnes of Waiblingen( 1072/ 73 – 24 September 1143), also known as Agnes of Germany, Agnes of Poitou and Agnes of Saarbrücken, was a member of the Salian imperial family. Through her first marriage, she was Duchess of Swabia; through her second marriage, she was Margravine of Austria.
title: Barthold A. Butenschøn Sr.
paragraph_text: Hans Barthold Andresen Butenschøn( 27 December 1877 – 28 November 1971) was a Norwegian businessperson. He was born in Kristiania as a son of Nils August Andresen Butenschøn and Hanna Butenschøn, and grandson of Nicolay Andresen. Together with Mabel Anette Plahte( 1877 – 1973, a daughter of Frithjof M. Plahte) he had the son Hans Barthold Andresen Butenschøn Jr. and was through him the father- in- law of Ragnhild Butenschøn and grandfather of Peter Butenschøn. Through his daughter Marie Claudine he was the father- in- law of Joakim Lehmkuhl, through his daughter Mabel Anette he was the father- in- law of Harald Astrup( a son of Sigurd Astrup) and through his daughter Nini Augusta he was the father- in- law of Ernst Torp. He took commerce school and agricultural school. He was hired in the family company N. A. Andresen& Co, and became a co-owner in 1910. He eventually became chief executive officer. The bank changed its name to Andresens Bank in 1913 and merged with Bergens Kreditbank in 1920. The merger was dissolved later in the 1920s. He was also a landowner, owning Nedre Skøyen farm and a lot of land in Enebakk. He chaired the board of Nydalens Compagnie from 1926, having not been a board member before that. He also chaired the supervisory council of Forsikringsselskapet Viking and Nedre Glommen salgsforening, and was a supervisory council member of Filharmonisk Selskap. He was a member of the gentlemen's club SK Fram since 1890, and was proclaimed a lifetime member in 1964. He was buried in Enebakk.
title: Ludwig von Westphalen
paragraph_text: Johann Ludwig von Westphalen( 11 July 1770 – 3 March 1842) was a liberal Prussian civil servant and the father- in- law of Karl Marx.
title: John Adams (merchant)
paragraph_text: John Adams( 1672 or 1673 – 1745) was an American- born Canadian merchant and member of the Nova Scotia Council. He was the father- in- law of Henry Newton( politician).
title: Archduke Otto of Austria (1865–1906)
paragraph_text: Archduke Otto Franz Joseph Karl Ludwig Maria of Austria (21 April 1865 – 1 November 1906) was the second son of Archduke Karl Ludwig of Austria (younger brother of Emperor Franz Joseph I of Austria) and his second wife, Princess Maria Annunciata of Bourbon-Two Sicilies. He was the father of Charles I of Austria, the last Emperor of Austria.
title: Peter Burroughs
paragraph_text: Peter Burroughs( born 27 January 1947) is a British television and film actor, the director of Willow Management. He is the father- in- law of actor and TV presenter Warwick Davis.
title: Ogawa Mataji
paragraph_text: Viscount was a general in the early Imperial Japanese Army. He was also the father- in- law of Field Marshal Gen Sugiyama.

Reasoning steps:
Agnes of Austria spouse Andrew III of Hungary
Andrew III father Stephen the Posthumous

Answer: spans: Stephen the Posthumous