Append SoftBody to RigidBody

[Coder-345]

I have 2 loaded meshes

1. Made into SoftBody
2. Another made to RigidBody

I want to attach certain vertices/faces/part of the SoftBody on to the RigiBody.
So whenever the RigidBody moves it moves along with it .

A similar eg file is given in : Appendanchor example demo
But in my code I wanted to append softbodies like : This SoftBody example demo

As in this example I want a part of sphere or cuboid softbody to append to the arm ..

In the example the appendAnchor() function works like :

SoftBody.appendAnchor( 0, arm.userData.physicsBody, false, influence );
SoftBody.appendAnchor( clothNumSegmentsZ, arm.userData.physicsBody, false, influence );

But in my case the rigidbody is constant but the softbody part to be appended to the rigidbody will vary in vertices / faces for each and everymesh .
How can I use the function to achieve what I want.

I am fairly new to ammo.js and bullet . So even small reference on appendAnchor would greatly help me..