See the discussion in the
Microsoft Word Catalogue/Directory Mailmerge Tutorial 'Sticky' thread at the top of this page (
https://www.msofficeforums.com/mail-...-tutorial.html) on the use of DATABASE fields in conjunction with a mailmerge. The article includes links to oher threads with examples. Depending on what you're trying to achieve, you may be able to the approach described there. It is possible to use more than one DATABASE field in a mailmerge maind document, each refencing a different data source.