How to create bones from PNG file?

I'm using the latest version of Unity and I also installed the 2D Animation and 2D IK packages.

I have my sprite parts all placed into one PNG file. So I imported that file, change the Sprite Mode to Multiple and with the Sprite Editor, I sliced it into the various parts. Everything works fine so far.

So then I change the view to Skinning Editor so that I can create the bones. However, the first problem is that I have to double-click on each sprite first, before I can add the bones. The second problem, which is even worst, is that I can't set up parent bones because the bones for every sprite are independent. I've seen tutorials where PSB files are imported and everything works fine. However I'm using GIMP.

Is there a way to move the sprites to form the character and then create bones for the whole character?

EDIT:
Currenty to animate the player, I move the sprites to the scene (under a Player GameObject), position them accordingly and then create animations with the Animation tool. This works but I'd like to use skeletal animation instead.

 

idk if pushing is allowed, but i have exactly the same problem!

 

I'm sorry for necroing, but I have this exact problem and I cannot find a solution. Tutorials seem to be for older versions of Unity and the options in the Sprite Editor and Skinning Editor are not the same so I can't simply follow the same steps...
How do I create a single bone structure for all body parts when using a PNG file?