How to replace footage between 2 layers of the same comp?

Basically I have 2 compositions. One with a lot of effects and duplicated layers of the background, and another that is with a single layer of the background, but with a different timecode. What I want to do is copy all the affected layers of the first comp and place in the second, but also I have to replace all the duplicated layers with this new background (but also with the right timecode).

I know there is a way I can replace the footage itself (which is not an option in this case), and another that I could only alt click from the source pannel and replace my layers. But if I do so, my layer footage that I've swaped always goes with a different timecode and I have to adjust it manually for each layer I've "ALT replaced".

I've been wondering if there is any script that could just replace a footage for another from the same comp, so that i could only replace all the footage with the old background.

***quick observation: i really need a quick method to do this, bc I need to replace another 40 comps, and each comps has its 50 layers stacked, so im looking for something that could be a one click replacing situation.