Question: Who is the sister of the Powderfinger composer?

full_context: Document 1: Cowgirl in the Sand: "Cowgirl in the Sand" is a song written by Neil Young and first released on his 1969 album "Everybody Knows This Is Nowhere". Young has also included the live versions of the song on several albums and on the Crosby, Stills, Nash and Young album "4 Way Street". It has also been covered by The Byrds on their self-titled album. Like two other songs from "Everybody Knows This Is Nowhere", "Cinnamon Girl" and "Down by the River", Young wrote "Cowgirl in the Sand" while he was suffering from the flu with a high fever at his home in Topanga, California.
Document 2: Life (Neil Young & Crazy Horse album): Life is an album by Canadian musician Neil Young and his backing band Crazy Horse, and it is Young's last release on the Geffen label. As with their 1979 album "Rust Never Sleeps", Young and the Horse performed most of this album's songs live with the exceptions of "Cryin' Eyes" and "We Never Danced" which were recorded in studio. The album was released on July 6, 1987.
Document 3: Hey Hey, My My (Into the Black): Sheff: You disagree with Neil Young's lyric in Rust Never Sleeps: ``It's better to burn out than to fade away... ''
Document 4: William Young (Nova Scotia politician): Born in Falkirk, the son of John Young and Agnes Renny, Young was first elected to the Nova Scotia House of Assembly in 1836 as a Reformer (or Liberal) and, as a lawyer, defended Reform journalists accused of libel. When responsible government was instituted in 1848, Young hoped to become the first Premier but was passed over in favour of fellow reformer James Boyle Uniacke and Young became Speaker. However, Young succeeded Uniacke in 1854.
Document 5: Jacob Richler: Jacob Richler is a Canadian newspaper and magazine journalist, and the son of novelist Mordecai Richler and Florence Isabel (Wood). He was the inspiration for his father's "Jacob Two-Two" trilogy of children's books.
Document 6: Rockin' in the Free World: "Rockin' in the Free World" is a song by Neil Young, released on his 1989 album "Freedom". Two versions of the song were released, similarly to the song "Hey Hey, My My (Into the Black)" of Young's "Rust Never Sleeps" album, one of which is performed with a predominantly acoustic arrangement, and the other with a predominantly electric arrangement. The song is now considered one of Neil Young's best songs. The song was ranked 216 on Rolling Stone's 500 Greatest Songs of All Time.
Document 7: James Young (Upper Canada politician): He was born in Nova Scotia in 1777 and settled in Ameliasburgh Township in Upper Canada. In 1808, he was named justice of the peace in the Midland District. He served in the local militia during the War of 1812 and became lieutenant colonel in 1824. He represented Hastings & Ameliasburg in the 6th Parliament of Upper Canada. He died at Carrying Place in 1831.
Document 8: Scott Young (writer): Scott Alexander Young (April 14, 1918 – June 12, 2005) was a Canadian journalist, sportswriter, novelist and the father of musicians Neil Young and Astrid Young. Over his career, Young wrote 45 books, including novels and non-fiction for adult and youth audiences.
Document 9: Jock Young: Jock Young was educated at the London School of Economics. His PhD was an ethnography of drug use in Notting Hill, West London, out of which he developed the concept of moral panic. The research was published as "The Drugtakers". He was a founding member of the National Deviancy Conferences and a group of critical criminologists in which milieu he wrote the groundbreaking, "The New Criminology: For a Social Theory of Deviance" in 1973, with Ian Taylor and Paul Walton and "The Manufacture of News" (with Stan Cohen).
Document 10: Rust Never Sleeps: Rust Never Sleeps is a live album by Canadian singer-songwriter Neil Young and American band Crazy Horse. It was released on June 22, 1979, by Reprise Records. Most of the album was recorded live, then overdubbed in the studio. Young used the phrase "rust never sleeps" as a concept for his tour with Crazy Horse to avoid artistic complacency and try more progressive, theatrical approaches to performing live.
Document 11: Pocahontas (song): "Pocahontas" is a song written by Neil Young that was first released on his 1979 album "Rust Never Sleeps". It has also been covered by Johnny Cash, Everclear, Emily Loizeau, Crash Vegas, Gillian Welch and Ian McNabb.
Document 12: Powderfinger (song): "Powderfinger" is a song written by Neil Young, first released on his 1979 album "Rust Never Sleeps". It subsequently appeared on several of Young's live recordings. A 2014 "Rolling Stone" special issue on Young ranked it as Young's best song ever.
Document 13: The Needle and the Damage Done: "The Needle and the Damage Done" is a song by Neil Young that describes the destruction caused by the heroin addiction of musicians he knew including his friend and Crazy Horse bandmate Danny Whitten. It previews the theme of the "Tonight's the Night" album that reflects Young's grief over the heroin overdose and death of both Whitten and Bruce Berry, a roadie for Young and Crazy Horse.
Document 14: Nick Sagan: Nick Sagan (born September 16, 1970 in Boston, Massachusetts) is an American novelist and screenwriter. He is the author of the science fiction novels "Idlewild", "Edenborn", and "Everfree", and his screen credits include episodes of "" and "". He is the son of astronomer Carl Sagan and artist and writer Linda Salzman.
Document 15: John Walter Scott: John Walter Scott (November 2, 1845 – January 4, 1919) of New York City, was originally from England, but he emigrated to the United States to take part in the California Gold Rush. Unsuccessful at the prospecting trade, Scott began to sell postage stamps for collectors and in a short period of time became the nation's leading stamp dealer. During his lifetime, he was known as "The Father of American Philately" by his fellow stamp collectors.
ground_truth: Astrid Young
sub_queries: Powderfinger >> composer Answer: Neil Young
Neil Young >> sibling Answer: Astrid Young