Grete Jalk or not?  

I am always suspicious when it comes to Grete Jalk attribution...
Looking at your links, the chairs do not look like the chairs designed by Jalk for France & Son or Poul Jeppesen which are documented in the furniture index. Furthermore, the second link mentions remains of a paper label which is not the way France & Son marked their funiture.
I would say neither Jalk nor France & Son but an actual picture of your chairs and additional details might help.

Oh, and I have noticed that both auctions took place in Germany and I see from your profile that you are in Germany as well. The chairs might be a german production in danish modern style. But that's just a guess...

I second DrPoulet. And I will go further and say they are NOT France and Søn. (And therefore very, very likely not Jalk designs).

Thanks for your comments, I supposed so too.
Anyway two points are remarkable, first the design of the armrests, they are exactly identic to the Jalk chairs, second the rubber straps, those rubber straps are typical of danish productions.

Here in France, there is a model of easy chairs that is commonly sold as Grete Jalk, even by famous galleries. They are very nice chairs, of really good quality and usually sell for quite a lot of money. They are unmarked and I have never seen any outside of France, where they are not too rare.
I bought one a year ago and made some research. It appears that these chairs are french AND danish. A French company called Fraska (confort FRAncais et design SKAndinave) imported wood and drawings from Denmark but the chairs and the cushions were made here in France.
I mean if the french were doing this kind of things, I don't see a reason why the same wouldn't exist in Germany, USA, etc.