1. Open a Word document, and click Review > Compare > Combine. See screenshot:

2. In the Combine Documents dialog, please:
(1) Click the Browse button besides the Original document box, select the original document you will merge in the Open dialog box, and finally click the Open button. See screenshot:
(2) Click the Browse button besides the Revise document box, select the revised document you will merge in the Open dialog box, and click the Open button.

3.Now in the Combine Documents dialog box, please click the More button to expand more options. See screenshot:

4. In the Combine Documents dialog box, (1) check the Comments option in the Comparison settings section, (2) check the Original document option in the Show changes section, and (3) click the OK button. See screenshot:

5. A Microsoft Word dialog pops up, please click Continue with Merge button. See screenshot:

And now you will see the original document has been combined with the first one of the checked document. See screenshot:
(1) The main changes and comments are shown in the left pane;
(2) The combined document is displayed in the middle section;
(3) The original document is show in above section of right pane, while the revised document is show in the below section.

Then repeat the above steps to combine all the checked documents

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