My wife and I are planning on taking the train from Munich to Heidelberg, thence to Frankfurt Airport the following day. I went to raileurope.com to make 1st Class reservations. The options for Munich-Heidelberg all had a connection of between six and nine minutes between trains. We are elderly, and I doubt we can debark, find the proper connecting train and board in such a short time. There doesn't seem to be much flexibility in the way the options are structured, i.e. connecting on a later train. My questions are: 1)is there another more flexible service than raileurope to possibly use; or, 2) if we missed our connection to Heidelberg whilst trying to find the connecting train in Mannheim, can we still grab a later train using our ticket for the original connection?
Rail Europe's timetables are incomplete. If you go to www.bahn.de, the German Rail site, you will see that there are five trains/day that go directly from Munich to Heidelberg. And if you book well in advance (up to 90 days allowed) on that site, you can get a Dauer-Spezial fare as low as €29 for 2nd class and €69 for 1st class. Those tickets are for a specific departure date and time and are non-exchangeable and non-refundable. But that shouldn't be a problem for you if you book one of the direct trains rather than connecting in Mannheim.
If you pay full fare, you can take any train you wish and you could take a later train if you miss a connection.
Although Tim's information is obviously what you want to go with here, I just want to point out that in the event you need to go with the trip through Mannheim for one reason or another, the train station is not very large and it is easy to change between trains. I had a ten-minute stopover and I was at the track and ready to go in less than three minutes.