Question: Who is the child-in-law of Marie De Namur?

Knowledge 1: Marie de Namur
Marie of Namur, also known as Marie de Namur or Maria van Dampierre.Her titles were "Gräfin von Vianden", from her first marriage and "Dame de Pierrepont", from her second marriage to, Theobald of Bar.Born in 1322 to John I of Namur and his wife Marie of Artois.She had three sisters, including Blanche of Namur, Queen consort of Sweden and Norway, and seven brothers.In 1335/36, she married her first husband, Henry II, Graf of Vianden, son of Philip II, Graf of Vianden and his first wife Lucia von der Neuerburg.Henry was murdered at Famagusta in September 1337.In c. 1337, she gave birth to Maria of Vianden her first daughter from her marriage to Henry II, Graf of Vianden.Her second marriage in 1340 (dispensation 9 September 1342) was to her father's second cousin, Theobald of Bar, Seigneur de Pierrepont, son of Erard of Bar, Seigneur de Pierrepontet d'Ancerville (himself son of Theobald II of Bar), and his wife Isabelle of Lorraine (daughter of Theobald II, Duke of Lorraine).This marriage produced two daughters, Yolande de Bar (b. c 1343 – d. c 1410) and Elisabeth de Bar (b. c1345 – d. before 11 May 1411).Marie died somewhere before 29 October 1353/57. [SEP] Knowledge 2: Elisabeth de Bar
Elizabeth of Bar also known as Elisabeth (Isabel) de Bar-Pierrepont, was born circa 1345 at Hagestein, Zeeland, Netherlands.She was the youngest daughter of Theobald de Bar, Seigneur de Pierrepont and his wife Marie de Namur.When her father, Theobald, died between 2 August 1353 and 6 July 1354.And because he had no legitimate male heir, she became the heiress of Bar-Pierrepont.She married Otto, Lord of Arkel, son of John IV, Lord of Arkel and Irmengard of Cleves, somewhere before 18 October 1360.They had one son, John V, Lord of Arkel, born on September 11, 1362 in Gorinchem.Elisabeth died before 11 May 1411 at Pierrepont, France.
Knowledge 1: Marie de Namur
Marie of Namur, also known as Marie de Namur or Maria van Dampierre.Her titles were "Gräfin von Vianden", from her first marriage and "Dame de Pierrepont", from her second marriage to, Theobald of Bar.Born in 1322 to John I of Namur and his wife Marie of Artois.She had three sisters, including Blanche of Namur, Queen consort of Sweden and Norway, and seven brothers.In 1335/36, she married her first husband, Henry II, Graf of Vianden, son of Philip II, Graf of Vianden and his first wife Lucia von der Neuerburg.Henry was murdered at Famagusta in September 1337.In c. 1337, she gave birth to Maria of Vianden her first daughter from her marriage to Henry II, Graf of Vianden.Her second marriage in 1340 (dispensation 9 September 1342) was to her father's second cousin, Theobald of Bar, Seigneur de Pierrepont, son of Erard of Bar, Seigneur de Pierrepontet d'Ancerville (himself son of Theobald II of Bar), and his wife Isabelle of Lorraine (daughter of Theobald II, Duke of Lorraine).This marriage produced two daughters, Yolande de Bar (b. c 1343 – d. c 1410) and Elisabeth de Bar (b. c1345 – d. before 11 May 1411).Marie died somewhere before 29 October 1353/57. [SEP] Knowledge 2: Robert II, Count of Namur
Robert II of Namur was Count of Namur from the death of his father in 1010 to some time between 1018 and 1031.He was the son of Albert I, and Ermengarde daughter of Charles, Duke of Lower Lorraine.
Knowledge 1: Marie de Namur
Marie of Namur, also known as Marie de Namur or Maria van Dampierre.Her titles were "Gräfin von Vianden", from her first marriage and "Dame de Pierrepont", from her second marriage to, Theobald of Bar.Born in 1322 to John I of Namur and his wife Marie of Artois.She had three sisters, including Blanche of Namur, Queen consort of Sweden and Norway, and seven brothers.In 1335/36, she married her first husband, Henry II, Graf of Vianden, son of Philip II, Graf of Vianden and his first wife Lucia von der Neuerburg.Henry was murdered at Famagusta in September 1337.In c. 1337, she gave birth to Maria of Vianden her first daughter from her marriage to Henry II, Graf of Vianden.Her second marriage in 1340 (dispensation 9 September 1342) was to her father's second cousin, Theobald of Bar, Seigneur de Pierrepont, son of Erard of Bar, Seigneur de Pierrepontet d'Ancerville (himself son of Theobald II of Bar), and his wife Isabelle of Lorraine (daughter of Theobald II, Duke of Lorraine).This marriage produced two daughters, Yolande de Bar (b. c 1343 – d. c 1410) and Elisabeth de Bar (b. c1345 – d. before 11 May 1411).Marie died somewhere before 29 October 1353/57. [SEP] Knowledge 2: Princess Marie of Hanover
Princess Marie of Hanover (2 December 1849 – 4 June 1904) was the younger daughter of King George V of Hanover and of his wife, Princess Marie of Saxe-Altenburg.

Answer: Otto, Lord of Arkel