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 the topic
Merging by Catalog/Directory to E-Mail in my
Microsoft Word Catalogue/Directory Mailmerge Tutorial in the 'Sticky' thread at the top of this forum:
Microsoft Word Catalogue/Directory Mailmerge Tutorial
or:
http://www.gmayor.com/Zips/Catalogue%20Mailmerge.zip
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 non-email worked examples, see the attachments to the posts at:
mail merge with duplicate names but different dollar amounts
Access to Word, Creating a list from multiple records
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
Microsoft services