Attach another object to a bone

[bandinopla]

What is the right way to append an object as a child of a bone?
I have loaded a model using the useGLTF hook, see it on screen, all good. The I load another static one, see it on screen all good. How can i make the 2nd object a child of some bone in the first object?

Tried doing it on a useEffect hook but the object just dissapears. Any idea?

Also this doesn't work(?) the object CupModel just dissapears...

    <primitive object={nodes.handBone}>
      <CupModel/>
    </primitive>

[bandinopla]

In case someone is looking for this, in the end the way I did it was on a useEffect hook:

  const { scene, animations } = useGLTF('/dude.glb')
  const clone = React.useMemo(() => SkeletonUtils.clone(scene), [scene])
  const { nodes, materials } = useGraph(clone) as GLTFResult
  const { scene: coffeCupScene } = useGLTF('/coffecup.glb')
...
  useEffect(() => { 

    if (nodes && coffeCupScene) 
    { 
      nodes.handBone.add(coffeCupScene) 
    }  

  }, [nodes, coffeCupScene]);