title: Three.js: How to add a skeleton as a child of another skeleton?
body: <p>I have to skeletons s1 and s2, each of them has its own bone array, SkinnedMesh, and animation.</p>
  
  <p>I'd like to know if it's possible to make s2 a sub skeleton of s1. i.e. set the root(b2) bone of s2 as a child of some bone (b1) in s1.</p>
  
  <p>I tryed <code>b1.add(b2);</code> but seems like matrix of s2 is not updated as s1 moves.</p>