Question: Who is the father-in-law of Margaretha Van Mechelen?

Knowledge 1: Margaretha van Mechelen
Margaretha van Mechelen (c. 1580 in Lier – 17 May 1662 in The Hague) was a noblewoman of the Southern Netherlands and (from c.1600 to c.1610)the mistress of Maurice of Nassau, Prince of Orange, with whom she had 3 sons:Though Maurice refused to marry her (probably because she was a Catholic and only from the minor nobility), he did state his intent to do so from his death bed (and to legitimise and marry off their children).This would threaten his half-brother Frederick Henry's place in the succession and so Frederick Henry summoned Amalia of Solms-Braunfels and married her a few days before Maurice's death. [SEP] Knowledge 2: Maurice, Prince of Orange
Maurice of Orange (14 November 1567 – 23 April 1625) was "stadtholder" of all the provinces of the Dutch Republic except for Friesland from 1585 at earliest until his death in 1625.Before he became Prince of Orange upon the death of his eldest half-brother Philip William in 1618, he was known as Maurice of Nassau.Maurice spent his youth in Dillenburg in Nassau, and studied in Heidelberg and Leiden.He succeeded his father William the Silent as stadtholder of Holland and Zeeland in 1585, and became stadtholder of Utrecht, Guelders and Overijssel in 1590, and of Groningen in 1620.As Captain-General and Admiral of the Union, Maurice organised the Dutch rebellion against Spain into a coherent, successful revolt and won fame as a military strategist.Under his leadership and in cooperation with the Land's Advocate of Holland Johan van Oldenbarnevelt, the Dutch States Army achieved many victories and drove the Spaniards out of the north and east of the Republic.Maurice set out to revive and revise the classical doctrines of Vegetius and pioneered the new European forms of armament and drill.During the Twelve Years' Truce, a religious dispute broke out in the Republic, and a conflict erupted between Maurice and Van Oldenbarnevelt, which ended with the latter's decapitation.After the Truce, Maurice failed to achieve more military victories.He died without legitimate children in The Hague in 1625, and was succeeded by his younger half-brother Frederick Henry.
Knowledge 1: Maurice, Prince of Orange
Maurice of Orange (14 November 1567 – 23 April 1625) was "stadtholder" of all the provinces of the Dutch Republic except for Friesland from 1585 at earliest until his death in 1625.Before he became Prince of Orange upon the death of his eldest half-brother Philip William in 1618, he was known as Maurice of Nassau.Maurice spent his youth in Dillenburg in Nassau, and studied in Heidelberg and Leiden.He succeeded his father William the Silent as stadtholder of Holland and Zeeland in 1585, and became stadtholder of Utrecht, Guelders and Overijssel in 1590, and of Groningen in 1620.As Captain-General and Admiral of the Union, Maurice organised the Dutch rebellion against Spain into a coherent, successful revolt and won fame as a military strategist.Under his leadership and in cooperation with the Land's Advocate of Holland Johan van Oldenbarnevelt, the Dutch States Army achieved many victories and drove the Spaniards out of the north and east of the Republic.Maurice set out to revive and revise the classical doctrines of Vegetius and pioneered the new European forms of armament and drill.During the Twelve Years' Truce, a religious dispute broke out in the Republic, and a conflict erupted between Maurice and Van Oldenbarnevelt, which ended with the latter's decapitation.After the Truce, Maurice failed to achieve more military victories.He died without legitimate children in The Hague in 1625, and was succeeded by his younger half-brother Frederick Henry. [SEP] Knowledge 2: Louis of Nassau, Lord of De Lek and Beverweerd
Louis of Nassau, Lord of De Lek and Beverweerd (1602 – The Hague, 28 February 1665) was a Dutch soldier.He was the illegitimate son of Margaretha van Mechelen and Maurice, Prince of Orange, and so a collateral member of the House of Orange-Nassau.He was a Lord of the heerlijkheid De Lek and .From his father he inherited the estate of Beverweerd; and when his older brother Willem died in 1627 he inherited his estate as well.
Knowledge 1: Margaretha van Mechelen
Margaretha van Mechelen (c. 1580 in Lier – 17 May 1662 in The Hague) was a noblewoman of the Southern Netherlands and (from c.1600 to c.1610)the mistress of Maurice of Nassau, Prince of Orange, with whom she had 3 sons:Though Maurice refused to marry her (probably because she was a Catholic and only from the minor nobility), he did state his intent to do so from his death bed (and to legitimise and marry off their children).This would threaten his half-brother Frederick Henry's place in the succession and so Frederick Henry summoned Amalia of Solms-Braunfels and married her a few days before Maurice's death. [SEP] Knowledge 2: Louis of Nassau, Lord of De Lek and Beverweerd
Louis of Nassau, Lord of De Lek and Beverweerd (1602 – The Hague, 28 February 1665) was a Dutch soldier.He was the illegitimate son of Margaretha van Mechelen and Maurice, Prince of Orange, and so a collateral member of the House of Orange-Nassau.He was a Lord of the heerlijkheid De Lek and .From his father he inherited the estate of Beverweerd; and when his older brother Willem died in 1627 he inherited his estate as well.

Answer: William the Silent