Postal Act Article 23

Where a mail item has more than one addressee, the said mail item may be delivered to any of them.Where there is dispute between the addressees prior to the delivery of said mail item and Chunghwa Post has received a statement to the effect that litigation has been initiated with respect to receipt of said mail item, delivery should be made in accordance with the confirmed judicial ruling or outcome of litigation.
中文原文 郵政法第23條
各類郵件之收件人有二人以上者,得向其中任何一人投遞之。
前項郵件在未投遞前,收件人間發生爭議,向中華郵政公司聲明,對於其郵件之收受已提起訴訟時,應依確定之判決或訴訟結果投遞之。

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