Asking Word to unscramble this is a bit much. For all anyone knows, the client's tracked changes are to content that you've already edited. Even if it isn't, should your edits take priority over changes the client hasn't made? Moreover, what if you and your client have made different changes to the same text - whose take's priority?

Your best approach at this stage would probably to be to accept all the changes the client made in their returned document, then compare that document against yours.

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Cheers,
Paul Edstein
[Fmr MS MVP - Word]