Administrative Litigation Act Article 32

The opposing party shall be notified about the appointment, designation, substitution, increase in number or cancellation of representative parties as provided in Article 29 and Article 30.
中文原文 行政訴訟法第32條
第二十九條及第三十條訴訟當事人之選定、指定及其更換、增減應通知他造當事人。

English translation for reference only; the Chinese text prevails. Not legal advice.