Code of Civil Procedure Article 137

When the person to be served cannot be found in his/her domicile/residence, office, or place of business, service may be effectuated by leaving the paper with his/her housemate or employee of suitable age and discretion.The provision of the preceding paragraph does not apply to cases where the housemate or employee is the opposing party.
中文原文 民事訴訟法第137條
送達於住居所、事務所或營業所不獲會晤應受送達人者,得將文書付與有辨別事理能力之同居人或受僱人。
如同居人或受僱人為他造當事人者,不適用前項之規定。

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