I'm using the latest version of Word, so hopefully what I'm about to suggest still makes sense with your version, so good luck!
I'd copy the four notes you have into four separate Word documents and save them as 'Note 1', 'Note 2', 'Note 3' and 'Note 4', ordered from oldest to newest if you know (but I don't think it necessarily matters). If it was a note to which you were primarily adding content, you could order them from fewest words to most.
With no documents open in Word, launch the 'Compare and merge documents' command and load 'Note 1' and 'Note 2'. You should have a number of panes open on screen, but the central one will show the merged notes, with strikethrough for deleted text and additions highlighted in a different colour. You should be able to work your way through, accepting and rejecting each of the changes, if any (sorry I can't help you with the finer detail of this, but hopefully you can work it out). Then, save this new document as 'Note 1&2' or similar and close it.
Now, run Compare and merge again, this time loading the new document 'Note 1&2' and 'Note 3', check and accept/reject the changes, saving the output as 'Note 1&2&3' (for example). Then go through for the final time, comparing 'Note 1&2&3' with 'Note 4'. With a bit of luck, the final output will be your resolved version.
I figured out this logic just now, since this isn't a problem I have had to face, so I'm happy for any of my colleagues to throw in your own ideas or dispute mine!
Let us know how you go.