Question: The Carlist Party of Euskalherria was historically part of the wing that was represented by which head of the House of Bourbon-Parma?

Context paragraphs:
Carlist Party (1970): The Carlist Party (Spanish language: "Partido Carlista", Catalan language: "Partit Carlí", Euskera: "Karlista Alderdia", Galician language: "Partido Carlista", Asturian language: "Partíu Carlista".  PC) is a Spanish political party that considers itself as a successor to the historical tradition of Carlism.  The party was founded in 1970, although it remained illegal until 1977, following the death of the dictator Franco and the democratisation of Spain.

Prince Carlos, Duke of Parma: Prince Carlos of Bourbon-Parma, Duke of Parma and Piacenza (born 27 January 1970) is the current head of the House of Bourbon-Parma, as well a member of the Dutch Royal Family.  He is the uncontested traditional claimant to the defunct throne of the Duchy of Parma under the name "Carlo V" (English: Charles V), and is a contested pretender to the Carlist claim to the throne of Spain under the name "Carlos Javier II" (English: Charles Xavier II).

History of Warwickshire: This is about the history of the county Warwickshire situated in the English Midlands.  Historically, bounded to the north-west by Staffordshire, by Leicestershire to the north-east, Northamptonshire to the east, Worcestershire to the west, Oxfordshire to the south and Gloucestershire to the south-west.  Areas historically part of Warwickshire include Coventry, Solihull, Sutton Coldfield and a small area of central Birmingham including Aston and Edgbaston.  These became part of the metropolitan county of West Midlands (Sutton Coldfield becoming part of Birmingham) following local government re-organisation in 1974 after the passage of the Local Government Act 1972.

Montejurra massacre: The Montejurra massacre, or less commonly, Montejurra incidents, was a neo-fascist terrorist attack that took place on May 9, 1976, when two Carlists militants were killed and another three seriously wounded by right-wing gunmen at the annual Carlist Party celebration that was held in Montejurra, Navarre, Spain.

Infanta Blanca of Spain: Infanta Blanca of Spain (7 September 1868 – 25 October 1949) was the eldest child of Carlos, Duke of Madrid, Carlist claimant to the throne of Spain and his wife Princess Margherita of Bourbon-Parma.  Blanca was a member of the House of Bourbon and - according to the Carlists - an Infanta of Spain by birth.  In 1889 she married Archduke Leopold Salvator of Austria.  The couple had ten children.  The family left Austria after the end of the Monarchy and finally settled in Barcelona.  When the male line of Blanca's family died out at the death of her uncle, Alfonso Carlos, Duke of San Jaime, some of the Carlists recognized her as the legitimate heiress to the Spanish throne.

Carlos Hugo, Duke of Parma: Carlos Hugo, Duke of Parma and Piacenza (8 April 1930 – 18 August 2010) was the head of the House of Bourbon-Parma from 1977 until his death.  Carlos Hugo was the Carlist pretender to the throne of Spain and sought to change the political direction of the Carlist movement through the Carlist Party, of which he was the official head during the fatal Montejurra Incident.  His marriage to Princess Irene of the Netherlands in 1964 caused a constitutional crisis in the Netherlands.

Carlist Party of Euskalherria: Carlist Party of Euskalherria (before 2000 Carlist Party of Euskadi (Basque: "Euskalherriko Karlista Alderdia" and Spanish: "Partido Carlista de Euskalherria" ; EKA) is a left-wing carlist Basque political party, with presence in the Spanish Basque Country.  The party was historically part of the pro-Carlos Hugo wing of the carlist movement.  The party wasn't legalized until late 1977.

Prince Xavier of Bourbon-Parma: Xavier, Duke of Parma and Piacenza, in France known before 1974 as Prince Xavier de Bourbon-Parme, in Spain known as Francisco Javier de Borbón-Parma y de Braganza or simply as Don Javier (25 May 1889 – 7 May 1977) was the head of the ducal House of Bourbon-Parma.  He is best known as dynastic leader of Carlism and the Carlist pretender to the throne of Spain, since 1936 as a regent-claimant and since 1952 as a claimant, appearing under the name Javier I.  Since 1974 he was pretender to the defunct throne of Parma.  He is also recognized as involved in the so-called Sixtus Affair of 1916-1917 and the so-called Halifax-Chevalier talks of 1940.

Infanta Adelgundes, Duchess of Guimarães: D. Infanta Adelgundes, Duchess of Guimarães (10 November 1858 – 15 April 1946) was the fifth child and fourth daughter of Miguel of Portugal and his wife Adelaide of Löwenstein-Wertheim-Rosenberg.  A member of the House of Braganza by birth, Adelgundes became a member of the House of Bourbon-Parma through her marriage to Prince Henry of Bourbon-Parma, Count of Bardi.  She was also the Regent of the Monarchic Representation of Portugal and for that reason was granted the title of Duchess of Guimarães, usually reserved for the Head of the House.

FET y de las JONS: The Falange Española Tradicionalista y de las Juntas de Ofensiva Nacional Sindicalista (FET y de las JONS) (English: "Traditionalist Spanish Phalanx of the Committees of the National Syndicalist Offensive") was the sole legal party of the Francoist dictatorship in Spain.  It emerged in 1937 from the merger of the Carlist Party with the Falange Española de las JONS, and was dissolved in 1977 by Adolfo Suárez's transitional government.

Supporting paragraphs: Carlist Party of Euskalherria Carlos Hugo, Duke of Parma
Answer: Carlos Hugo, Duke of Parma