Complex sentence: D'Andrade and his brother were then engaged as singers at the Théâtre Privé d'Opéra in Moscow for the 1885/86 season and he also appeared in St. Petersburg and Warsaw.
Split into simpler sentences: D'Andrade and his brother were then engaged as singers at the Théâtre Privé d'Opéra in Moscow for the 1885/86 season. During that time he also appeared in St. Petersburg and Warsaw.