Transferring Notes From Kindle for PC Between Machines
However, if you are using a DRM-Free book, it's quite easy to transfer your notes.
Please note - I am using Kindle for PC (Windows version) here. I run it in a virtual machine on my linux box; most of my clients and authors run Windows, so that's what this guide focuses on. Click to embiggen pictures.
First, make sure you are showing hidden files. You'll simply move the .mobi file to My Kindle Content - and when you make notes (or highlights) it will create a file with the same name but a .mbp extension.
Then, it's as simple as sending both files (and you can probably get away with just the MBP file) to the other person, and they'll see your notes throughout the book:
BDAOW. No confusion, no muss, no fuss.
I'm sure there's a way to get the MDP file from a Kindle and/or (unlocked) phone; if anyone has guides to that, it'd be vastly appreciated.