Getting a 3D Reflection across multiple objects?

Freesnel does nothing for flat surfaces. It would look like a simpole gradient overlay. To make your screens more "tangible" they will need to look liek physical objects, which means they need thickness or a frame. Even a paer photo has a thin edge that catches light, you know. and of course one might want to add irregularities within the photos themselves like a slight curvature illusion with some subtle gradient effect. In your case you could also add a light from behind and above to mimic sun glare just like you could add tiniest variation to the tilt and positioning to the images to make them look less like a repeat but rather a human has laid them out.

Mylenium

I would build a huge pre-comp and animate the "light sources" within it while assigning the pre-comp as a static environment map. That's the most art-directable approach.

Mylenium