You can change the previous invention into a utility model by claiming the priority, but the previous invention will be revoked, and vice versa. As long as the application for substantive examination is submitted, you can enter the substantive examination procedure. The application for substantive examination can be submitted at the same time as the patent request, or after receiving the relevant notice from the Patent Office. . .
There are generally two ways to apply for foreign patents, through the Paris Convention or PCT. There are many details in this regard. If you apply for it yourself, it is easy to have problems. It is recommended to entrust an agency to handle it. . .
Hope to adopt!