You can use Word's Catalogue/Directory Mailmerge facility for this (the terminology depends on the Word version). To see how to do so with any mailmerge data source supported by Word, check out my
Microsoft Word Catalogue/Directory Mailmerge Tutorial:
https://www.msofficeforums.com/mail-...-tutorial.html
The tutorial covers everything from list creation to the insertion & calculation of values in multi-record tables in letters. Do read the tutorial before trying to use the mailmerge document included with it.
Depending on what you're trying to achieve, the field coding for this can be complex. However, since the tutorial document includes working field codes for all of its examples, most of the hard work has already been done for you - you should be able to do little more than copy/paste the relevant field codes into your own mailmerge main document, substitute/insert your own field names and adjust the formatting to get the results you desire. For some worked examples, see the attachments to the posts at:
https://www.msofficeforums.com/mail-...html#post23345
https://www.msofficeforums.com/mail-...html#post30327
Another option would be to use a DATABASE field in a normal ‘letter’ mailmerge main document and a macro to drive the process. An example of this approach can be found at:
Many to one email merge using tables - Microsoft Community
Conversely, if your workbook has a separate sheet with just a single instance of each of the grouping criteria, a DATABASE field in a normal ‘letter’ mailmerge main document could be used without the need for a macro. For an example of that, see:
Mail Merge - To a Word Table on a Single Page - Microsoft Community
The DATABASE field can even be used without recourse to a mailmerge. An example of such usage can be found at:
https://www.msofficeforums.com/mail-...html#post67097
Alternatively, you may want to try one of the Many-to-One Mail Merge add-ins, from:
Graham Mayor at
Merge Many To One or
Doug Robbins at
http://bit.ly/1hduSCB