Finn Juhl for John Stuart  

I will also note that I have not seen the factory printed John Stuart name on a France and Son production, only FD. There is also this mark that claims JS as the "sole distributor for the usa". I'm only guessing that this relationship became less exclusive.

I don't know how exclusive the relationship stayed and for how long. The value of exclusive rights to France and Søn's line became would have gone up over the next decade after that stamp was put on a chair.
I don't have any other US catalogs that show France and Søn stuff, so I suppose it is possible that JS remained the exclusive distributor for a while.
I have also seen a John Stuart stamp on a Søborg piece that indicated JS was the exclusive USA retailer.