exchange eticket in rail office airport

Good mornig

I want to buy tickets from
beiking-pingyao
pingyao-xian
....
....
more or less 5 journeys in 15 days.
I don´t know if is possible to book and pay these tickets in Internet and when I will be in Beijing Airport (Railway Office), exchange the booked for the true ones. But all of them at the same time.

Or if the delivery company can send me all at the hotel in Beijing.

Thank you so much