I’m not really certain if I can follow your ideas here. Your image showed the Motion-Tag and underlined the Layer entry. OK, not the layer, it is the PSR.
The Clips in each layers are not copies. In the Moment you open the clip in a new Timeline, you open the source. Where ever the clip was used in this set up, it will change things as well.
If you need to change something, the clip, if used not only once, need to be copied. However, open it (or several) in the Timeline will not show the changes made in duration nor in speed.
To change the “events” in a clip, without changing the source, you click in the Clip, or many of them and go to the advanced mode. But the Spline interface will not make a difference among them, each from start to end will be adjusted.
To get a set up managed in the way I understand your idea so far, select all the clips in question, “right mouse click” and chose Convert Motion Clip to Motion Source. This new clip has now only one entry for each channel i.e., PSR. This can be opened in the Dope or F-Curve and be adjusted. In F-Curve mode this will even allow for the “Reduced Modification Mode”. This will not change the previous source clips. The animation for those can be switched off (Film Stripe Icon) and a new layer with the combined information can be applied.
Again, I can’t really say that I got a clear idea of what your want to do so far. Anyway, I hope some one the content above might help or fit. Without a scene file, I guess we will not make any progress other than this.
Perhaps that is something for the suggestion form:
https://www.maxon.net/en-us/support/suggestions/
My best wishes