So 1st pc 4090 will be master with front view, set up with zoom in place where you want.
and determent to seat position by translate left or right (right or co pilot by default)
Now 2nd client pc 4070ti 2 screens 1 left and 1 right
Depend on where you have positioned and derterment your main frontview on masterpc
The 2nd pc (client) has main window it is up to you if it will be the left or the rightview.
But for what you decide from there setup zoom to match the master pc and position with translate on this client.
When it it zoomed and positioned to your liking, bring up the experimental multiscreen in ui and create a 2nd window on the client pc. Then drag this to the second screen on the client, once position the window set it up with the sliders to where it needs to be, (the zoom is set and will be followed by 1st screen as described above.
Though there are more ways possible in different situations (like setup outside the airplane)
Make sure on both pc you have the same airplane for the setup
And try to set the same general overall settings