G fast train with kids?

Hello,
I am planning a family trip to China in April-2017, and I would to use the fast G ride from Shanghai to Beijing and return.
I understand that my 8 year old daughter will need to buy a ticket at half price, and my 2 year old son does not need pay for a ticket. But does he still need to have a (free) ticket to pass security, enter in the ride, etc?
Thanks.