Potential Itinerary for family of 7

Day 17 Train to Frankfurt to fly home

You plan to take train from Nurnburg and fly the same day ( to the US?)? If so, I believe I am with the majority here that would recommend against such a plan. ( If flight is 3PM or later it may be a reasonable choice)

Seeing the word 'train' listed on 10 of the 17 days, seems like a lot.

Way too many day trips for me. This itinerary is exhausting! Looks like you are going to experience life on a train, rather than Germany and its people. Consider also, that traveling with a 2 year old adds an entire different dimension to being constantly on the go from one place to another. I would advise that you slow down...prioritize what you want to see and do while in Germany. I may be in the minority, but Fussen/Neuschwanstein would be the first thing to be eliminated. IMO, the best part was the view of the castle from the road. The tour of the castle was short and not worth fighting the hordes of tourists. Also, you don't have much time to explore Munich.

Freudenstadt is a KONUS town but not the most central base town for your outings. The Black Forest Railway is a main artery through the most interesting part of the Black Forest and is one of Germany's most scenic train rides. You'd be better off if you stayed RIGHT ON the Black Forest Railway somewhere. See map. Hausach, Haslach, Gengenbach, Hornberg and Gutach (home of the Black Forest Open-air Museum and summer bobsled run, not shown on the map but near Hausach) would all be good choices with good train connections.

We stayed in Steinach (also on the BF Railway, near Haslach but not shown on that map) a few years ago in an apartment (5 persons max) on a farm within easy walking distance of the Steinach train station - it was great. Herr Schöner speaks English and was friendly and helpful. The family also has a "Giebelzimmer" - a tiny mini-apartment for 1 or 2 on the top floor - so perhaps they could accommodate you all. I would encourage you to contact Herr Schöner by email to see whether his place meets your needs and whether he has availability for your dates. You'll find a few photos and email contact info at this page.

Right now you have a lot of overnight time in very big cities. I think using Munich and Stuttgart as base towns for those long day trips by train is maybe ill-advised. Suggest you keep 2 days of sightseeing in Munich w/ Dachau (if that makes for a good vacation in your eyes) and maybe 3 nights there instead of 6. Then go somewhere else for 3 nights. Berchtesgaden is a long day trip. You might look into combining your alpine interests into one spot; with a base in or near Oberammergau, it would be possible to day trip to Füssen, to Garmisch and Mittenwald, and to other places by public transport without the long return to Munich every day. I don't think Weltenburg is particularly easy as a day trip from Munich either - have you checked? You may want to visit Andechs instead, an easier day trip from Munich.

The best destination near FRA (about 1 hour by train) is the Middle Rhine Valley - not Heidelberg or Frankfurt - in my very subjective opinion. The MRV outshines Stuttgart, Esslingen, and the Black Forest as well. I'd want 3 nights there, either at the beginning or the end of your trip.

This has been very helpful. I should probably add this information about the trip's goal. I want to show my children where I lived as a child. That is why Heidelberg, Stuttgart/Esslingen and Munich are on the schedule. The rest of the places are more global to give them a feel of the scenary and culture. I love the idea of moving from Freudenstadt to Steinach as Russ suggested. I will contact Herr Schőner, do you know if they have laundry facilities?
I thought about staying in Mittenwald, but I thought it would be easier to stay one place and not move luggage so often. Rick Steve's 2018 book stated that Berchtesgarten and Fussen/Neuschwanstein were daytrips from Munich.
I know it may seem like we have alot of train trips, my memory of German trains is that they are comfortable, great scenery and no driver missing the views as well as on schedule 90% of the time. Has that changed?

"Rick Steve's 2018 book stated that Berchtesgarten and Fussen/Neuschwanstein were daytrips from Munich."

What constitutes a doable day trip is a matter of opinion of course. Rick seems to think that 5 hours for the round trip (which is what it takes to get to Berchtesgaden and back by train) and nearly 5 hours for N'stein (on both trains and buses - and for a mere 30-minute tour of N'stein) is an acceptable way to spend your vacation time. I don't agree with him. Generally speaking, I don't consider day trips that require more than 3-4 hours maximum. (I think a lot of experienced travelers in Germany would agree that Rick's generalizations about Germany are often worth questioning; it's wise to get additional information in forums like this and from other guidebooks too.)

You can find accurate travel times yourself by looking at the DB itinerary page (which includes trains and buses.)

Berchtesgaden is how you spell it when you do your search.

Schöner farm: We did not require a washing machine during our stay and don't remember seeing one. But this alternative commercial listing in German indicates that there is a washing machine on the premises that you can use. You can find more pics there as well. And you can ask Herr Schöner about that. Before booking independently with any innkeeper anywhere in Germany, be sure to ask about cancellation (Stornierung) policy. Your may or may not be able to cancel without an obligation to pay - I don't know in this case.

"The rest of the places are more global to give them a feel of the scenary and culture." I think you'll get more scenery and sometimes more culture if you stay a few more nights in somewhat smaller cities and towns - Book in Esslingen over Stuttgart for example, and book a few nights in a place like Oberammergau or Berchtesgaden in lieu of Munich...

Your 2 year old will marvel at all of the train stations you will be visiting and become an expert on the trains' WCs. I wouldn't recommend this itinerary for 1 adult let alone 6 adults and a toddler.

With the exception of Heidelberg, you will be traveling a long way and spending a lot of money to see very little.

If you find that you are getting tired of ridng trains, then take a day of leisure in your week in Munich.