Administrative Procedure Act Article 30

Any election or replacement, or the increase or decrease of the number, of a party or parties, shall have no effect without giving the administrative authority a written notice thereof.Any assignment or replacement, or the increase or decrease of the number, of a party or parties made by an administrative authority shall have no effect without a written notice thereof served upon all parties with common interest; provided that a public announcement may be made in lieu of the notice if it is evidently difficult to give such notice.
中文原文 行政程序法第30條
當事人之選定、更換或增減,非以書面通知行政機關不生效力。
行政機關指定、更換或增減當事人者,非以書面通知全體有共同利益之當事人,不生效力。
但通知顯有困難者,得以公告代之。

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