Short answers, pulled from the story.
Alfred Einstein was a German-American musicologist and music editor born in Munich on the 30th of December 1880 and died on the 13th of February 1952. He is best known for editing the first major revision of the Kochel catalogue of Mozart's works, published in 1936, and for his 1945 book Mozart: His Character, His Work.
The Kochel catalogue is the comprehensive listing of all compositions by Wolfgang Amadeus Mozart, originally compiled by Ludwig von Kochel. Alfred Einstein produced the first major revision of the catalogue in 1936, making it the work for which he is most widely remembered.
Alfred Einstein was Jewish and fled Germany in 1933 after Hitler's rise to power placed him in direct danger. He moved first to London, then to Italy, and finally arrived in the United States in 1939.
After emigrating to the United States, Alfred Einstein held teaching positions at Smith College, Columbia University, Princeton University, the University of Michigan, and the Hartt School of Music in Hartford, Connecticut.
The relationship is disputed. Alfred's daughter Eva stated in 1991 that they were not related, but wrote in 2003, based on research by George Arnstein, that they were fifth cousins on one side and fifth cousins once removed on the other. The two men were photographed together in 1947 but did not know at that time that they were distantly related.
Critics identified two problems: Einstein promoted a romanticized view of Mozart, including the claim that Mozart's last three symphonies were never performed, which Neal Zaslaw refuted with extensive evidence in 1994. Einstein also over-relied on stylistic analysis to date Mozart's works; Wolfgang Plath's handwriting studies and Alan Tyson's watermark research later revealed serious errors in his datings.