Answer
Yes, Leopold II had other siblings besides Marie Antoinette. He had 15 siblings in total, including his seven full siblings and eight half-siblings from his father's first marriage. His full siblings included Archduchess Maria Christina, Archduchess Maria Elisabeth, Archduchess Maria Carolina, Archduke Ferdinand, Archduchess Maria Anna, Archduke Maximilian Franz, and Archduke Karl.