As if “Sonya Alone†didn’t already sound like a perfect Ingrid Michaelson song, it will soon be sung by Michaelson herself. The singer-songwriter will join the cast of Broadway’s Natasha, Pierre & the Great Comet of 1812 from July 3 to August 15 this summer to play Sonya, the tortured cousin of Natasha, played by Denée Benton. Brittain Ashford, who originated the role, will return on August 16 to the musical, which was nominated for 12 Tony Awards and won two last Sunday. Michaelson will join Hamilton’s Oak Onaodowan, who will replace Josh Groban in the role of Pierre, also starting July 3.