And, then there's the French?European writing of the number 9 with the under-stroke. To my American-English-only eyes looks like a "g".
While living in areas of France, Belgium, and/or Luxembourg and learning to write (guessing 1930s-1940s) either she was not taught to use the upstroke on the number 1 nor the understroke on 9. OR she dropped the use of these strokes as an adult.
'Either way seem odd to me. I think it's difficult to just drop handwriting styles learned as a child... but I know only American/English writing. And, likely shouldn't speculate on any this again. lol
It may all hinge on when she was born and the age at which she moved.
The latest thinking puts her birth between 1926 and 1934 (1930 +/- 4 years).
So if she was born in 1926 her family would have moved in 1930. Although the Nazi Party was not elected to national government until 1933 my understanding is that the Nuremburg area was a hotbed of Nazi Party activity before then so it's possible the family fled activity in the Nuremburg area but didn't necessarily feel the need to flee Germany completely. So maybe her parents, or at least her father, was involved in Leftist politics or trade union activities.
If she was born in 1930, then it's possible the family fled after the elections which brought the Nazi Party to power, in which case they probably did flee across the border into France or Luxembourg. The question then would be what they did after 1940 when Germany invaded northern France, Luxembourg, Belgium and the Netherlands. Where could they have gone to? The UK is probably ruled out by the fact that the Isdal Woman is reported to have spoken very poor English. Sweden and Switzerland were both neutral and would have been safe but there's no indication that she spoke Swedish.
If she was born as late as 1934, then Kristallnacht in 1938 could have been the trigger to the family moving when she was around 4 years old.
This is of course assuming her family was fleeing the Nazis. Her father could simply have been in the sort of job that could have had him posted from one part of the country to another, such as an engineer or railway worker or in the military in some capacity.
In any event, if she was only 4 when the family moved she would have been below school age so would have learned her handwriting
after her migration to the France/Luxembourg/Belgium area, and the style was sufficiently engrained for it to have remained for life.
I think if they exhume her body as part of the investigation, isotope tests on her hair would help to fill in the blanks in her movements during the last 18 months of her life.