Hi tie-version,

As far as I understand what you like to do, here is a suggestion. (Storyboards are more the way to share those ideas; words are always a basis of interpretation)

Each shape is stored in a Spline, which is part of the Blend settings of the Cloner. The Plain Effect drives the progress of the Blend> Modify Clones.

The Null sets the main motion, the Plain effector, and then the "morph" defines the change of each shape over time.

Here is a quick demo:

I used the Mesh> Move> Magnet Tool to shape the "subframe-spline".

The best base to get very fast with this is to study Rotoscoping. In a nutshell, it separates shapes into forms with the least amount of change and moves them from the "keyframe" (the point of main change, PSR).

Besides the Cloner, the PoseMorph Tag might be the way to go. The Point-level Animation (PLA) seems more accessible for the first run-through but becomes increasingly difficult to adjust.

All the best