Code of Civil Procedure Article 461

Where the appeal is voluntarily dismissed or dismissed on the ground that it is not filed in conformity with the law, the incidental appeal shall be inoperative. Notwithstanding, an incidental appeal satisfying the requirement of an ordinary appeal shall be deemed an independently operative appeal.
中文原文 民事訴訟法第461條
上訴經撤回或因不合法而被駁回者,附帶上訴失其效力。
但附帶上訴備上訴之要件者,視為獨立之上訴。

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