Managing answer version history / answer archives

Content

Any tips/best practices on how to manage answer version history? 

For example: An answer needs updated because a new feature has been added to a product or some words have been changed to make the answer more customer-friendly.  For legal purposes, we need a version of the answer that illustrates what's changed on the answer (a version history if you will).

I've been using the "Notes" tab but am wondering if there is a more efficient way? Or, is there a way to create a copy of the original answer and attach it to the updated answer, highlighting what has been modified?