This seems like a common question but I can't find anyone talking about it.
I made a very complex armature, spent a couple days on it, only to realize the root bone (I call handle) is in the wrong place. It is in the middle of the spine, I want the "butt" bone to be the new root bone so that I can bend the spine normally. Messing with parenting in edit mode doesn't seem to work or is too complicated for me.
Here is the .blend file:
And a screenshot:
How do I fix this ?