Juan de la Cerda, 5th Duke of Medinaceli
Juan de la Cerda, 5th Duke of Medinaceli( 1544 – 29 May 1594), Grandee of Spain,( in full), was a Spanish nobleman and Ambassador in Portugal.
He was the son of Don Juan de la Cerda, 4th Duke of Medinaceli and of Joana Manuel, daughter of Sancho de Noronha, 2nd Count of Faro.
In 1565 he married Donna Isabella d’ Aragona, daughter of Don Antonio d’ Aragona, 2nd Duke of Montalto with whom he had two children.
In 1580, he married for a second time, with Juana de la Lama, 4th Marchioness of la Adrada, a widow since 1571 of Don Gabriel de la Cueva, 5th Duke of Alburquerque, deceased as a Governor of the Duchy of Milan, Italy, with whom he had two more children.
Isabel de la Cerda
Isabel de la Cerda also known as" Isabel de la Cerda Pérez de Guzmán"( Seville c. 1329- after 1383) was the only surviving daughter of Luis de la Cerda and his first wife Leonor de Guzmán; she was Lady of Puerto de Santa María and titular Princess of Fortuna.
She was a member of the House de la Cerda.
Philip of Castile, Lord of Cabrera and Ribera
Philip of Castile (Seville, 28 May 1292 – Madrid, April 1327), was an "infante of Castile", son of Sancho IV of Castile and María de Molina.
He was Lord of Cabrera and Ribera and regent of his nephew Alfonso XI of Castile.
He married his cousin Margarita de la Cerda, daughter of Alfonso de la Cerda.
Juan de la Cerda, 4th Duke of Medinaceli
Juan de la Cerda, 4th Duke of Medinaceli (c. 1514 – 1575), Grandee of Spain, was a Spanish nobleman.
He was the son of Don Juan de la Cerda, 2nd Duke of Medinaceli, by second wife María de Silva.
In 1552 Juan de la Cerda inherited the titles from his older half-brother Gastón de la Cerda y Portugal.
Both half brothers, the 3rd, Gaston, and the 4th Duke, Juan II, are widely reported in many places and articles as being born "out of marriage" from different women and being "legitimated" males by the Crown as legal successors to their father, the second duke Juan I, also, apparently, a legitimated bastard, however.
In 1557, King Philip II of Spain appointed him Viceroy of Sicily, a position he held until 1564.
During that time he besieged with a fleet the North-African harbor of Tripoli, now in Libya, dealing with Dragut, a Turkish privateer and Ottoman admiral.
The force, including ships from Spain, Genoa, Tuscany, the Knights of Malta and the Papal States, was however nearly destroyed in the Battle of Djerba.
In 1567 he was appointed Viceroy of Navarre supposedly staying there till 1572, but it seems that towards the end of 1570, he became head of the household of Queen Anna of Austria, position he held until his death in 1575.
In the spring of 1572 Philip II sent Medinaceli to the Netherlands as governor.
According to Henry Kamen, Medinaceli reported to the king that "“Excessive rigour, the misconduct of some officers and soldiers, and the Tenth Penny, are the cause of all the ills, and not heresy or rebellion.”
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One of the governor’s officers reported that in the Netherlands "“the name of the house of Alba”" was held in abhorrence.
Medinaceli lobbied the King for the removal of the Duke of Alba as military commander.
Deciding that the views of Medinaceli and Alba were not compatible, Philip II removed both and replaced them with Requesens.
Ferdinand de la Cerda, Lord of Lara
Fernando de la Cerda( 1275 – 1322) was the younger son of Ferdinand de la Cerda, Infante of Castile and his wife Blanche of France.
His elder brother was
Sancho de la Cerda, 1st Marquis of la Laguna
Sancho de la Cerda, 1st Marquis of la Laguna, (in full), (c. 1550 – 14 November 1626) was a Spanish nobleman and diplomat.
Sancho was the third son of Don Juan de la Cerda, 4th Duke of Medinaceli and of his wife
Doña Joana Manuel de Portugal.
He joined the royal household, and rose to become Spanish Ambassador to Flanders, member of the council of state and of the council of war under King Philip III and later head of the household of his wife, Queen Margaret of Austria.
He was rewarded with the title of "Marquis of la Laguna de Camero Viejo" on 16 February 1599.
Luis de la Cerda, 1st Marquis of Cogolludo
Luis de la Cerda, 1st Marquis of Cogolludo( in full)( c. 1506 – 1536) was a Spanish nobleman.
He was the eldest son of Don Juan de la Cerda, 2nd Duke of Medinaceli, by first wife Mencía Manuel de Portugal.
He married Ana de Mendoza, Lady of the Nueve Lugares de la Cuadrilla de Sierra- Alta del Ducado de Medinaceli, without issue.
Charles de La Cerda
Charles de La Cerda, commonly known as Charles of Spain( 1327 – 8 January 1354 in L'Aigle), was a Franco- Castilian nobleman and soldier, the son of Alfonso de la Cerda" of Spain"( died 1327) and Isabelle d' Antoing, and grandson of Alfonso de la Cerda" the disinherited"( 1270 – 1333).
He was a distant cousin of John II of France.
A boyhood companion and favorite of John while he was Duke of Normandy, Charles commanded the Castilian galleys at the Battle of L'Espagnols- sur- Mer, where he was defeated by Edward III of England after a long and desperate struggle.
Soon after John's accession to the throne, he was appointed Constable of France, filling the vacancy left by the execution of Raoul II, Count of Eu, and created Count of Angoulême.
Vacant since the death of Joan II of Navarre in 1349, the title to Angoulême was claimed by her son, Charles II, King of Navarre, who bitterly resented La Cerda's preferment.
In 1351, Charles de La Cerda married Marguerite, a daughter of Charles, Duke of Brittany.
In 1354, Charles of Navarre and several members of his household set upon and slew de la Cerda in an inn.
The repercussions of this murder led to a continuous state of instability within France that was only resolved upon the accession of Charles V in 1364.
Francisco José de Ovando, 1st Marquis of Brindisi
Francisco José de Ovando y Solís Rol de La Cerda, 1st Marquis of Brindisi  (c. 1693 – December 9, 1755) was a Spanish soldier who served as governor of Chile.
Nepomuceno de la Cerda
Nepomuceno de la Cerda( 1752–1826) was a Spanish soldier of note, after whom the town of La Cerda, Texas, was named.

Question: Who is Sancho De La Cerda, 1St Marquis Of La Laguna's paternal grandfather?
Answer: Juan de la Cerda, 2nd Duke of Medinaceli