The Labor Incident Adjudication Rules Article 21

This English translation was last updated on 2019-11-15, but the Chinese text was amended on 2023-08-23. Later amendments may not be reflected in the translation — please refer to the Chinese text.

A third party who has an interest in a labor mediation case may participate in the labor mediation procedures with the judge's permission; the judge may also notify interested third parties concerning the case and order such third parties to participate.
中文原文 勞動事件審理細則第21條
就勞動調解事件有利害關係之第三人,經法官許可,得參加勞動調解程序;法官並得將事件通知之,命其參加。

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