Harmony lets you extend your rigging techniques beyond normal boundaries and sets new standards. You can create hierarchies without encapsulating pieces inside each other by creating a linked structure between layers.
You should create a hierarchy on the arms and legs, and keep them separated from the body. This gives you more animation freedom, and when you need to scale or skew the torso, it will not affect the entire body.
|‣||Drag the child piece (hand) and drop it ON the parent piece (forearm). Then, you can drag the parent (forearm) piece onto another parent piece (upper arm).|
|‣||See Nudging Parts Backwards and Forwards to reorder parts that should be in front of their parents.|
Here is a basic rig with pegs example: