How do I link armature on separate objects to work together? I have created a character with separate objects for arms/legs/body/head.

I can add an armature to each object separately and they all work independently, they are not connected to each other but I would like to somehow link the arms/legs/head to the body so that when I move the body the rest move with it. 

How do I link armature in different objects so they work with each other?
So I got this going with a little help from a video tutorial, here is the quick run down:


Add an armature single bone.
Press E to extrude a new bone from the first bone.
Press ALT+P to detach the bone.


You can then move it and parent the bone to different objects but they remain linked and still work together when you pose them.

Credit goes to this video - https://www.youtube.com/watch?v=B9iL1hmJXrI&amp;t=153s&amp;list=WL&amp;index=6