Senior Moderator, Moderator: Community Buzz and Ambassador: Miles & More (Lufthansa, Austrian, Swiss, and other partners)
Join Date: Jun 2005
Location: 150km from MAN
Programs: LH SEN** HH Diamond
Posts: 29,514
As long as the train you are booked on stops at Bonn I think you can get on and off there. On the way back make sure to check in online before the train leaves Köln.