train ticket fr gl to gz

Hi. Would like to ask, I want to purchase ticket fr guilin to guangzhou for an overnight trip with sleeping deck. Question is we r 5 people, my 3 girls, one is 122 cm, 127 cm n 155 cm. So how many tickets do I need to buy? Can my 155 cm girl 12 y o still can purchase children fare? N my 122 cm can still free? Pls advice. N one more can all of us stay in one room?