hello, I am traveling from Luzerne to Wengen, via PE train to interlaken Ost. However, I would like to stop at Brienz and take a break. By purchasing a point-to-point ticket on the travel date, am I allowed to take off at Brienz, and get on a later PE train to interlaken on the same date? If it is allowed without extra charge, what happens to our reservation of seats? i.e. I know I need to reserve for seat for PE train, what happens when we get on a later train from Brienz to continue our journey? Thank You.