Sunshade in Rear Door Windows

Hi folks,
I am inclined to retrofit the shades in the rear doors of my A6 Avant (the baby will like it). It's just a replacement of the rear door trim, no big deal.
Now the only thing my dealer is still working out is how the hook at the top of the frame is attached.
Now for the question: If any of you has those shades in the rear door trims, could you please look up how they are attached?
1999 Audi A6 Avant TDI

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