Question: Whose composer father formed a friendship with Chopin?

full_context: Document 1: Siegfried Wagner: Siegfried Wagner (6 June 18694 August 1930) was a German composer and conductor, the son of Richard Wagner. He was an opera composer and the artistic director of the Bayreuth Festival from 1908 to 1930.
Document 2: Frédéric Chopin: Chopin seldom performed publicly in Paris. In later years he generally gave a single annual concert at the Salle Pleyel, a venue that seated three hundred. He played more frequently at salons, but preferred playing at his own Paris apartment for small groups of friends. The musicologist Arthur Hedley has observed that "As a pianist Chopin was unique in acquiring a reputation of the highest order on the basis of a minimum of public appearances—few more than thirty in the course of his lifetime." The list of musicians who took part in some of his concerts provides an indication of the richness of Parisian artistic life during this period. Examples include a concert on 23 March 1833, in which Chopin, Liszt and Hiller performed (on pianos) a concerto by J.S. Bach for three keyboards; and, on 3 March 1838, a concert in which Chopin, his pupil Adolphe Gutmann, Charles-Valentin Alkan, and Alkan's teacher Joseph Zimmermann performed Alkan's arrangement, for eight hands, of two movements from Beethoven's 7th symphony. Chopin was also involved in the composition of Liszt's Hexameron; he wrote the sixth (and final) variation on Bellini's theme. Chopin's music soon found success with publishers, and in 1833 he contracted with Maurice Schlesinger, who arranged for it to be published not only in France but, through his family connections, also in Germany and England.
Document 3: Cosma Shiva Hagen: Cosma Shiva Hagen (born May 17, 1981 in Los Angeles, California) is a German-American actress and the daughter of the German new wave/punk singer Nina Hagen and the Dutch musician Ferdinand Karmelk. Her grandmother is actress Eva-Maria Hagen, and her step-grandfather is the East German dissident writer Wolf Biermann. Eva-Maria Hagen was allowed to emigrate to West Germany during the 1970s. Shiva's unusual name was picked by her mother, who claimed she saw a UFO while pregnant. "Cosma" is a reference to Cosmos, and "Shiva" is a reference to the Hindu God Shiva.
Document 4: Frédéric Chopin: In his native Poland, in France, where he composed most of his works, and beyond, Chopin's music, his status as one of music's earliest superstars, his association (if only indirect) with political insurrection, his love life and his early death have made him, in the public consciousness, a leading symbol of the Romantic era. His works remain popular, and he has been the subject of numerous films and biographies of varying degrees of historical accuracy.
Document 5: Emma Seehofer: Emma Seehofer (before 1854 – 1912) was a German operatic contralto who was a principal artist at the Bavarian State Opera in Munich from 1854 to 1887. She created the roles of Erda in Richard Wagner's "Das Rheingold" on 22 September 1869 and Schwertleite (one of the Valkyries) in Wagner's "Die Walküre" on 26 June 1870. She was also highly active as a concert singer. After retiring from the stage, she worked as a singing teacher in Munich. She died at Mannheim.
Document 6: Cosima Wagner: Cosima Wagner (born Francesca Gaetana Cosima Liszt; 24 December 1837 – 1 April 1930) was the illegitimate daughter of the Hungarian pianist and composer Franz Liszt and Marie d'Agoult. She became the second wife of the German composer Richard Wagner, and with him founded the Bayreuth Festival as a showcase for his stage works; after his death she devoted the rest of her life to the promotion of his music and philosophy. Commentators have recognised Cosima as the principal inspiration for Wagner's later works, particularly "Parsifal".
Document 7: Tannhäuser (opera): Tannhäuser (; full title Tannhäuser und der Sängerkrieg auf Wartburg, "Tannhäuser and the Minnesingers' Contest at Wartburg") is an 1845 opera in three acts, music and text by Richard Wagner, (WWV 70 in the catalogue of the composer's works) based on two German legends: Tannhäuser, the legendary medieval German Minnesänger and poet, and the tale of the Wartburg Song Contest. The story centers on the struggle between sacred and profane love, and redemption through love, a theme running through much of Wagner's mature work.
Document 8: Frédéric Chopin: At the age of 21 he settled in Paris. Thereafter, during the last 18 years of his life, he gave only some 30 public performances, preferring the more intimate atmosphere of the salon. He supported himself by selling his compositions and teaching piano, for which he was in high demand. Chopin formed a friendship with Franz Liszt and was admired by many of his musical contemporaries, including Robert Schumann. In 1835 he obtained French citizenship. After a failed engagement to Maria Wodzińska, from 1837 to 1847 he maintained an often troubled relationship with the French writer George Sand. A brief and unhappy visit to Majorca with Sand in 1838–39 was one of his most productive periods of composition. In his last years, he was financially supported by his admirer Jane Stirling, who also arranged for him to visit Scotland in 1848. Through most of his life, Chopin suffered from poor health. He died in Paris in 1849, probably of tuberculosis.
Document 9: Frédéric Chopin: Jones comments that "Chopin's unique position as a composer, despite the fact that virtually everything he wrote was for the piano, has rarely been questioned." He also notes that Chopin was fortunate to arrive in Paris in 1831—"the artistic environment, the publishers who were willing to print his music, the wealthy and aristocratic who paid what Chopin asked for their lessons"—and these factors, as well as his musical genius, also fuelled his contemporary and later reputation. While his illness and his love-affairs conform to some of the stereotypes of romanticism, the rarity of his public recitals (as opposed to performances at fashionable Paris soirées) led Arthur Hutchings to suggest that "his lack of Byronic flamboyance [and] his aristocratic reclusiveness make him exceptional" among his romantic contemporaries, such as Liszt and Henri Herz.
Document 10: August Conradi: Conradi probably met Liszt in the early 1840s. He served as Liszt's copyist in Weimar in January and February 1844, and he spent 18 months there in 1848 and 1849 at Liszt's instigation. Conradi prepared copies of the initial versions of Liszt's orchestral works, making suggestions on scoring. He also assisted Liszt in assembling a "Programme general" of all the repertory he had played during his virtuoso years. While Conradi was an extremely hard worker, he also possessed a somewhat routine mind. When he received his appointment as Kapellmeister in Stettin in the winter of 1849, his work at Weimar was taken over by the more imaginative Joachim Raff. Nevertheless, Liszt continued to use him as a copyist. In September, 1855 Liszt wrote of his intention to send the score of his "Psalm 13" to Berlin so that Conradi could make a fair copy for the first performance there.
Document 11: Luise Willer: Luise Willer (1888–1970) was a German operatic contralto. She made her professional opera debut in 1910 as Annius in Wolfgang Amadeus Mozart's "La clemenza di Tito". She spent most of her career performing at the Bavarian State Opera in Munich. At the Bayreuth Festival, she portrayed Brängane in "Tristan und Isolde". She created roles in several world premieres during her career, including Barbara in Erich Wolfgang Korngold's "Violanta" (1916), Lukrezia in Hans Pfitzner's "Palestrina" (1917), Graben-Liese in Franz Schreker's "Das Spielwerk" (1920), and Herzogin in Pfitzner's "Das Herz" (1931) among others.
Document 12: Frédéric Chopin: With his health further deteriorating, Chopin desired to have a family member with him. In June 1849 his sister Ludwika came to Paris with her husband and daughter, and in September, supported by a loan from Jane Stirling, he took an apartment at Place Vendôme 12. After 15 October, when his condition took a marked turn for the worse, only a handful of his closest friends remained with him, although Viardot remarked sardonically that "all the grand Parisian ladies considered it de rigueur to faint in his room."
Document 13: Frédéric Chopin: Two Polish friends in Paris were also to play important roles in Chopin's life there. His fellow student at the Warsaw Conservatory, Julian Fontana, had originally tried unsuccessfully to establish himself in England; Albert Grzymała, who in Paris became a wealthy financier and society figure, often acted as Chopin's adviser and "gradually began to fill the role of elder brother in [his] life." Fontana was to become, in the words of Michałowski and Samson, Chopin's "general factotum and copyist".
Document 14: Frédéric Chopin: Although this period had been productive, the bad weather had such a detrimental effect on Chopin's health that Sand determined to leave the island. To avoid further customs duties, Sand sold the piano to a local French couple, the Canuts.[n 8] The group traveled first to Barcelona, then to Marseilles, where they stayed for a few months while Chopin convalesced. In May 1839 they headed for the summer to Sand's estate at Nohant, where they spent most summers until 1846. In autumn they returned to Paris, where Chopin's apartment at 5 rue Tronchet was close to Sand's rented accommodation at the rue Pigalle. He frequently visited Sand in the evenings, but both retained some independence. In 1842 he and Sand moved to the Square d'Orléans, living in adjacent buildings.
Document 15: Oliver Hilmes: Oliver Hilmes (born 1971 in Viersen, Germany) is a German author who has written several historical biographies. His study of Cosima Wagner, the daughter of the 19th century composer Franz Liszt and his biography of Alma Mahler a Viennese-born socialite, have been translated into English.
ground_truth: Cosima Wagner
sub_queries: What other composer did Chopin develop a friendship with? Answer: Franz Liszt
Franz Liszt >> child Answer: Cosima Wagner