To add cross reference in footnotes in MS Word

To insert a footnote at multiple places:

1. Click where you want to insert the footnote.
2. On the References menu, in the Footnotes group, click Insert Footnote.

   

3. Type the footnote text at the bottom of the page, as shown in the following figure:                                        
4. On the Insert menu, in the Links group, click Cross-reference. 
5. In the Cross-reference dialog box, from the Reference type box, select Footnote.
6. In the Insert reference to box, select Footnote number (formatted).
7. In the For which footnote box, select the footnote you want to insert and then click Insert.                    

The footnote that you want will be inserted as a cross-reference with a superscript just like a footnote.