For the most part, I recommend keeping only one copy of a document, letting each reviewer make his or her changes in turn, and then reviewing those changes at the end. Sometimes, however, it is necessary to let a document go to two or more reviewers at the same time.
Word provides two features for consolidating the changes in multiple copies of a document: Merge Documents and Compare Documents. Both work only on changes that have been tracked. Changes made when Track Changes is turned off cannot be merged or compared.
If a copy of a document contains changes that were made while Track Changes was not turned on, Word warns you before merging them into the master document with an option to cancel the operation or to merge changes up to the first unmarked change.
For both the merge and compare features, Word brings changes from a document that is not open into a document that is open (let’s call the open document the master copy):
Merge the changes from one copy into the master copy using Tools → Merge Documents. The changes and comments from both copies are shown in the merged document, just as if each author had edited the same document. If there are more than two copies of a document to merge, you must merge changes from one document at a time into the master copy.
Compare one copy of a document with another using Tools → Track Changes → Compare Documents. Word inserts the changes and comments from one copy into the master copy, but marks them ...