We are travelling on the same train but heading to different cities. Can we still sit together?

My friend and I are taking the G type from Beijing South but I am headed to Jinan and she's going to Qingdao. We booked tickets and we got seats in different carriages. Is there still a way for us to have seats next to each other?

Also both of us are going to have more than 20 kg of luggage, is there going to be a problem with it? Where do we put large suitcases if the racks are not large enough?