Few other updates since I met some German friends since this thread was last active.

Friend in Argentina (now Mexico) is 3rd generation German born in Argentina (as is his wife) so dual Argentinean and German citizens. Very strong connection to Germany maintained so not only are the children registered as German but sent to German school certified by Berlin (or Bonn) of which there are around 80 in Argentina.

Friend in Germany was born there and emigrated as a child. Acquired Canadian citizenship as a minor because her parents did it for her and lost her German citizenship then. However since she was a minor at that time, she could and did reapply for German citizenship, and got to retain her Canadian one (so some hope for one of the previous posters). Her husband is also a German citizen but born in Italy of German emigrant parents. So their German-born children are German, Italian and Canadian citizens.