Recording 16ch Focusrite with Adat problems with line outputs

[ProDrumFreak]

Dear forum members Good Morning,

FOH Yamaha O3D table (old one)
Focusrite sound 18i20
Adat card Behringer ADA8000

Our goal, 16-channel recording during the practice or recording live gigs.

Connecting the adat card on the focusrite went well. I can record 16 channels that's not the problem.
What I want is the following,

8 x Mic / Instrument in the focusrite and over the line output to the FOH «« «This works fine (line in« »Line Out)
8 x Mic / Instrument in the Behringer through the line output to the FOH «« «this does NOT work, I get no signal true the line outputs. With the Scarlett Mix control I can setup the sound (of Behringer) via a line output from the focusrite but that's not what I want.

I want a line in signal from the Behringer to a channel on my table. So I can EQ etc.

I have no 8 aux that I could do it the other way on my old Yamaha table.

What do you recommend me, I'm desperate at the moment. I want to be able record all 16 channels but also see the channels back on the FOH.

here some pictures
https://static.afbeeldinguploaden.nl/1603/153158/SDOp5hku.jpg
https://static.afbeeldinguploaden.nl/1603/153159/aAgofkCC.jpg
https://static.afbeeldinguploaden.nl/1603/153160/tVM3OItM.jpg
https://static.afbeeldinguploaden.nl/1603/153157/fw8fDH5b.jpg

Rgrds,

Jack