Question: Who is Magdalene Of Jülich-Cleves-Berg's father-in-law?

Sibylle of Jülich-Cleves-Berg
Sibylle of Jülich- Cleves- Berg, Margravine of Burgau( 26 August 1557 in Cleves – 1628 in Günzburg) was the daughter of Duke William the Rich and his second wife, Archduchess Maria of Austria.
Her brother John William inherited the United Duchies of Jülich- Cleves- Berg in 1592.
After he had developed a mental illness, a power struggle broke out at court between Sibylle and her sister- in- law Jakobea of Baden.
Sibylle won, and imprisoned Jakobea.
Sibylle may also have been partially responsible for Jakobea's violent death in 1597.
In 1601, Sibylle married Margrave Charles of Burgau.
In 1610, the couple moved into the residence at Günzburg.
Here, she entertained a feudal court, even after her husband died in 1618.
She acted in particular as patron of music.
Sibylle died in 1628 and was buried next to her husband in the Capuchin Church in Günzburg.
When the church was demolished, her remains were transferred to the St. Martin's Church, also in Günzburg.
Magdalene of Jülich-Cleves-Berg
Duchess Magdalene of Jülich-Cleves-Berg (2 November 1553 – 30 August 1633) was the fifth child of Duke William
"the rich" of Jülich-Cleves-Berg and Maria of Austria, a daughter of Emperor Ferdinand I.
She married in 1579 with Count Palatine John I "the lame" of Zweibrücken.
Emperor Charles V had in 1546 granted the Duchy of Jülich-Cleves-Berg the right of female succession.
So, when her brother, Duke John William, died in 1609 without a male heir of his own, both she and William's daughters could play a vital role in the question of who would inherit the important northwest German territory.
Magdalene's husband John claimed the inheritance for Palatinate-Zweibrücken, as did the Elector of Brandenburg, John Sigismund, who was married to Anna, a daughter of Magdalena's sister Marie Eleonore
(John Sigismund claimed his marriage contract from 1573 gave him the best claim).
The third claimant was Count Palatine Philip Louis of Neuburg, the husband of Magdalen's other sister Anna.
Finally, the Duchy of Saxony claimed Jülich-Cleves-Berg, based on an agreement to that effect with the Emperor.
Since all claimants were members of comprehensive European coalitions and so the Habsburgs and France were indirectly involved, an international conflict threatened:
the War of the Jülich succession.
However, after King Henry IV of France died, the conflict could be settled provisionally by the Treaty of Xanten.
The duchy was divided between Brandenburg and Palatinate-Neuburg.
In the meantime, Magdalena's husband had died in 1604 and his claim had been inherited by her eldest son John II (1584–1635), who did not receive a share under the Treaty of Xanten.
Magdalene's daughter Elisabeth (1581–1637) married Georg Gustav, Count Palatine of Pfalz-Veldenz.
She also had two younger sons: Frederick Casimir (1585–1645) and John Casimir (1589–1652).
She died in 1633 and was buried in the Reformed Church of Meisenheim.
Karl Friedrich of Jülich-Cleves-Berg
Charles Frederick of Jülich- Cleves- Berg( 28 April 1555 in Cleves – 9 February 1575 in Rome), was Hereditary Prince of the United Duchies of Jülich- Cleves- Berg and the counties of Mark and Ravensberg.
Sibylle of Cleves
Sibylle of Cleves (17 January 1512 – 21 February 1554) was electress consort of Saxony.
Born in Düsseldorf, she was the eldest daughter of John III of the House of La Marck, Duke of Jülich "jure uxoris", Cleves, Berg "jure uxoris", Count of Mark, also known as de la Marck and Ravensberg "jure uxoris" (often referred to as Duke of Cleves) who died in 1538, and his wife Maria, Duchess of Julich-Berg (1491–1543).
Her younger siblings were two sisters, Anne (later Queen of England) and Amalia, and a brother, William, who became Duke of Jülich-Cleves-Berg.
Duke Johann Wilhelm of Saxe-Altenburg
Duke Johann Wilhelm of Saxe- Altenburg( born 13 April 1600 in Torgau; died: 2 December 1632 outside Brzeg) was a member of the Ernestine branch of the House of Wettin and a titular Duke of Saxe- Altenburg and of Jülich- Cleves- Berg.
John I, Count Palatine of Zweibrücken
John I of Zweibrücken (known as the Lame; ; 8 May 1550 – 12 August 1604) was Count Palatine and Duke of Zweibrücken during 1569–1604.
He was born in Meisenheim as the second son of Wolfgang, Count Palatine of Zweibrücken and his wife Anna of Hesse.
In 1588 he changed the state religion from Lutheranism to Calvinism.
He died in Germersheim in 1604 and was buried in the Alexanderkirche in Zweibrücken.
William, Duke of Jülich-Cleves-Berg
William of Jülich- Cleves- Berge( William I of Cleves, William V of Jülich- Berg)( 28 July 1516 – 5 January 1592) was a Duke of Jülich- Cleves- Berg( 1539 – 1592).
William was born in and died in Düsseldorf.
He was the only son of John III, Duke of Jülich- Cleves- Berg, and Maria, Duchess of Jülich- Berg.
William took over rule of his father's estates( the Duchy of Cleves and the County of Mark) upon his death in 1539.
Despite his mother having lived until 1543, William also became the Duke of Berg and Jülich and the Count of Ravensberg.
From 1538 to 1543, William held the neighbouring Duchy of Guelders, as successor of his distant relatives, the Egmond dukes.
Emperor Charles
V claimed this duchy for himself as the dukes had sold their right of heritage, and William tried to hold on to it.
He made a treaty with the King of France and married Jeanne d'Albret, and with this backup dared to challenge the Emperor.
All too soon he learned that the French did not lift a finger to help him, and he was overwhelmed and had to surrender.
In accordance with the Treaty of Venlo( 1543) that was the result of this war, Guelders and the County of Zutphen were transferred to Charles V, Holy Roman Emperor, combining them with the Habsburg Netherlands.
William then tried to strengthen his inherited territories and launched an impressive development project for the most important cities.
The three duchies all got new main fortresses as major strongpoints, for the older medieval fortifications had proved to be no match against the Imperial artillery.
The cities of Jülich, Düsseldorf and Orsoy became fortresses for the duchies of Jülich, Berg and Cleves respectively, and Jülich and Düsseldorf were turned into impressive residences.
For this task, the renowned Italian architect Alessandro Pasqualini from Bologna was hired, who had already made some impressive display of his craft in the Netherlands.
He made the plans for the fortifications and palaces, of which some traces still remain, especially at Jülich where the citadel( built 1548- 1580) is a major landmark, with parts of the Renaissance palace still standing.
William's sister Anne of Cleves was, for six months, the fourth wife of King Henry VIII of England.
Through his daughter Marie Eleonore, he is ancestor of Marie Louise of Hesse- Kassel, wife of John William Friso, Prince of Orange therefore ancestor of all the current European monarchs.
Maria of Austria, Duchess of Jülich-Cleves-Berg
Archduchess Maria of Austria (15 May 1531 – 11 December 1581) was the daughter of Emperor Ferdinand I from the House of Habsburg and Anna Jagiello.
She married William, Duke of Jülich-Cleves-Berg on 18 July 1546 as his second wife.
Their children were:
John William, Duke of Jülich-Cleves-Berg
Johann Wilhelm of Jülich- Cleves- Berg( 28 May 1562 – 25 March 1609) was a Duke of Jülich- Cleves- Berg.
His parents were William" the Rich", Duke of Jülich- Cleves- Berg( 1516 – 92) and Maria of Austria( 1531 – 81), a daughter of Ferdinand I, Holy Roman Emperor and Anna of Bohemia and Hungary.
He grew up and was educated in Xanten.
Johann Wilhelm became Bishop of Münster.
However, after the unexpected death of his elder brother Karl Friedrich, Wilhelm was needed to succeed his father as Duke of Jülich- Cleves- Berg, a secular fief.
He was also Count of Altena.
The United Duchies of Jülich- Cleves- Berg was a combination of" reichsfrei" states within the Holy Roman Empire.
Johann Wilhelm was first married in 1585 to Jakobea of Baden( d. 1597), daughter of Philibert, Margrave of Baden.
He was secondly married to Antonia of Lorraine( d. 1610), daughter of Charles III, Duke of Lorraine.
He was subject to mental illness, for which he was treated by the physician Francesco Maria Guazzo.
Upon Duke Johann William's death in 1609, his inheritance was claimed by the heirs of his two eldest sisters: the heir of Maria Eleonora of Cleves( 1550 – 1608), the eldest sister and married to Albert Frederick, Duke of Prussia, was Anna of Prussia, the Electress of Brandenburg, a Protestant.
The second sister was Anna of Cleves( 1552 – 1632), married with Philipp Ludwig, Count Palatine of Neuburg, and her son and heir was the then Count Palatine of Neuburg, a Catholic.
The disputes of the epoch between Protestants and Catholics escalated, leading to the Thirty Years' War in 1618; the succession dispute became part of the war.
Ultimately, Brandenburg received Cleves- Mark and Neuburg received Jülich- Berg, after the lands had been trampled under military several times and lost much of the fabled wealth so renowned in Duke Wilhelm's time.
Among his court servants and employees were the composer Konrad Hagius.
Marie Eleonore of Cleves
Duchess Marie Eleonore of Cleves (16 June 1550 – 1 June 1608) was a Duchess consort of Prussia by marriage to Albert Frederick, Duke of Prussia.
She was the eldest child of William, Duke of Jülich-Cleves-Berg and Maria of Austria.

Answer: Wolfgang, Count Palatine of Zweibrücken