There is a question of priority. If we can understand the priority thoroughly, we won't have much problem understanding this patent of the same family.
PS: Patent priority refers to that the patent applicant filed a patent application for his invention and creation in a country for the first time, and then filed a patent application for the same theme for his invention and creation within the statutory time limit. According to the relevant laws and regulations, the date of the first patent application is the filing date of his later application, and this right enjoyed by the patent applicant according to law is the priority. The purpose of patent priority is to exclude the possibility that anyone who plagiarizes this patent in other countries may first apply and get registered.