Enforcement Rules for the Act Governing Relations between Peoples of the Taiwan Area and the Mainland Area Article 66

Where all the heirs are People of the Mainland Area and where one or several of the heirs apply for and acquire the inheritance of property rights that are required to be registered, such heirs shall not apply for the registration thereof until other heirs have waived the right of inheritance or have been deemed to waive the right of inheritance.
中文原文 臺灣地區與大陸地區人民關係條例施行細則第66條
繼承人全部為大陸地區人民者,其中一或數繼承人依本條例第六十六條規定申請繼承取得應登記或註冊之財產權時,應俟其他繼承人拋棄其繼承權或已視為拋棄其繼承權後,始得申請繼承登記。

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