Thanks for the file, gentib, I got it this morning, very much appreciated.
I have used the frame and camera view from your scene. However, I have replaced the part 1 and part 2 for clarity with just the number 1 and 2.
It can’t be rendered in one take, but in two.
I have created a Mask-Box, which is one time below the object and the other time above the second object. A Multi-Pass based Object Buffer creates the needed masks then.
Since there are many elements in this scene, I have created a short overview clip.
Scene file and clip: (updated scene file_03)
https://www.amazon.com/clouddrive/share/shW64bRPoXMR8QNydz1og1UwP04TSq9Jut4ZvN6V6I5
Clip was recorded with v01 of this file
https://www.amazon.com/clouddrive/share/nFmPovrlK5dOlGmiKbnnwLTl7Wi85OnwnehrwQqJmX0
When these two are rendered out, they can be easily combined in Ae or any comp-app. I have the frame in it during both renderings, as I was not clear if they catch any reflections in the scene. Otherwise, the Mask-Boxes can be closer and give only half of the frame each time.
I hope that helps.
Cheers
updated