Hi reading-card,

The key problem would be that the Polygon where the Root is will be lifted. Hence the results look somewhat chaotic.
If you could connect the points of the hair instances with the "main body", then the Polygon would be inside of it. Meaning you have three polygons sharing a single edge. This will not provide excellent results.
There is, of course, the idea of having two "main bodies" animated in the same way, preferably via PLA.
With this, one would have the Root information, and the other would receive the results. However, the Hair instances are generated, and I'm unclear on how to combine them and have those working with SDS.

Hence my suggestion with the Joint Rig.