This is where the topology output comes into play. If you connect it to a Polygons Topology Get node it provides the connection between a vertex and it's matching UV coordinate, as well as the UV polygons (outlines), which can be quite different from the geometry polygons.
@LuBaphomet
You have a couple of options here. One is using IK, constraints and parenting (haven't tried) or doing a math based rig. Here is a stab at it. It is all apcked in single mesh, you can check the graph for details. There are two sliders which do what you have been describing. Hope you can adapt it or transfer to your specifics.
slide_fun.c4d
Thanks to your answer I moved forward a lot so thank you.
Before I forget here is a quick tutorial to show your technique with the Brush tool in Smooth mode :
Given the clothing and possible mesh beneath it, and the possibility of intersections, it might be quite tedious to move it to T-pose first, so I think in this instance I would rig it in A-pose from the get-go.
Nice dog in avatar BTW ! 🙂
CBR
Here is a free node which interprets particle data. This means you can import particle attributes into Neutron graph by particle group and do what you want with it : )
228_Neutron_Particle_Import.c4d