How to secretly help others upgrade the high-speed rail?

Of course. There are three ways to upgrade the high-speed rail. The first way is that if the high-speed rail ticket booked online has not been changed to the paper ticket at the station, you can enter the booking website 2 hours before the high-speed rail starts and press the change button. You can check whether there is an upgrade ticket on the change page and change it according to the instructions on the website. The second method is to apply for an upgrade at the manual ticketing window in high-speed railway station with a paper high-speed rail ticket. The staff at the ticket window will check whether there is an upgrade ticket for you, and if there is, provide your identity and make up the balance of the upgrade.