Kushal Das

You should be putting the primitive group of the constraint you're trying to increase the rest length of into the 'Group' parameter of the Vellum Constraint Properties. Right now it's increasing the rest length of every constraint. You can create the group on the 'Output Group' parameter of the Vellum Constraints SOP.

Try packing all the curves using the Assemble sop and then point deforming. The smaller branches will stay rigid but will update orientation/position and follow your wire sim.

Assuming you don't have changing topology, unpack the rbd objects and try using a soft Pin to Target constraint and check on the option for "Match Animation".