1. First of all, two people's names can be written on the patent. Furthermore, the contract can prove that a patent was jointly invented by two people, but since it is proved that it was jointly completed, both people have the right to apply. If a person does not want another person to be an applicant, he can ask another person to write a declaration of giving up the patent right, so that only one person can apply, and after authorization, the patent right belongs to the applicant.
If you can't trust your friends completely, you'd better apply in person. To apply for a patent, you can write the materials and send them directly to China National Intellectual Property Administration without anyone's care. But you have to be able to write patent documents.