My wife and I will be in Berlin a week from today and have a pre-paid ticket to take the train from Berlin to Frankfurt. The train we booked has a change at Erfurt. I was looking at the schedule today and there is a nonstop train leaving Berlin going to Frankfurt 30 minutes later and arriving just a few minutes later but with no change of trains. Will DB allow us to take the later train and not have to change trains using the ticket we have already purchased in exchange for one on the later train? Just wondering. Thanks.
Yes for a fee.
It depends of the type of ticket you have. A flex price ticket is freely exchangable, a saver fare ticket can be cancelled against a fee of €19, and the price of your new ticket would be subject to the actual conditions (i.e. most likely more expensive).
For details see https://www.bahn.de/hilfe/view/pk/en/ticketbuchung/erstattungen.shtml