You have to write the application documents first. You can download the form from China National Intellectual Property Administration website. If you can't write it yourself, you can find a patent agency, but don't find that pheasant agent. You are not qualified, but the agency fee will be higher. The second question is basically hopeless, because you didn't apply for a patent, but you did, so there is no ownership of rights, which proves that it is meaningless that he designed it first.
Without application, there is no ownership, and it is meaningless to prove that you designed it first.
You can call the Intellectual Property Rights Protection Center at 12330 for consultation.