Hi nadja,
There has been a number of posts in this forum (and in numerous others) on this topic.
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, in the 'Sticky' thread at the top of this forum:
Microsoft Word Catalogue/Directory Mailmerge Tutorial
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.
For a recent, worked example, see the attachment to post #13 at:
https://www.msofficeforums.com/mail-...nt-dollar.html
Alternatively, you may want to try the Many to One utility on the MergeTools Add-in that you can download from the following page of Doug Robbins' Windows Live SkyDrive:
Microsoft OneDrive - Access files anywhere. Create docs with free Office Online.