From Paris, to Judi Missel,
Hirschfeld isn't a so common name in France.
So I check for living descendants in France with our official white pages : https://www.118712.fr/
I get 12 persons named "Hirschfeld", including one living in Strasbourg and a company, also in Strasbourg.
Other results are persons living in a "Hirschfeld street" in a town not far from Strasbourg.
These results include their phone & home address : I never try to call because it's impossible to explain within a few seconds why we contact, and these unknown persons will hang up immediately...
So I did it often, I send as many letters as I got addresses, a nice letter with copies of some family documents to explain my search.
Once, 17 letters to homonyms of a person in Zurich who had filled a page of testimony in Yad Vashem, 20 years ago.
Believe it or not, three days later, a lady call me with these simple words : "for 60 years, we were asking ourselves if your branch had any survivors ?"...
Archives & history of Medem Center - Arbeter Ring (Bund) of France