Fred:
It sounds like you have a much treasured experience.
What you said about Americans being able to speak older dialects of German is
not unusual. The immigrants were not exposed to many of the day to day
changes that took place in Germany, hence their German never changed.
An example of this occurred several years ago when the Swedish government
went to a town in Minnesota to record an old dialect of Swedish which no
longer existed in Sweden.
The Library of Congress has a branch which does nothing but record dialects
of old or even thought to be lost languages which still exist in the U.S.
The library has some unbelievable recordings from the Appalachian areas.
I mentioned in an earlier listing that a town near where I grew up (Manning
Iowa) is having a Low German conference in October this year.
Gale