For the change of 3C certificate, you can only change it if you provide the change certificate or relationship statement (from a third party) from two factories. For details, you can consult the engineer in the product department of China Quality Certification Center, tell him your situation, and then ask what kind of certificate you need to provide. Trademark, I suggest you don't reflect the trademark on the 3C certificate, but use it in accordance with the relevant provisions of the Trademark Law.