Design considerations:

Use a template - a Word Template
"Template" is a term of art in Word. It means, for the most part, a special kind of document that no one is supposed to type in. It is a holder of formatting, styles, and boilerplate text. If the user double clicks on it, it does not open. Instead a new document is created, holding all of the text and formatting of the template and having any customizations from the templates. It makes it more difficult for someone to mess up your form by mistake. Templates in Microsoft Word

One field per label.
If I were doing a mail merge, I would definitely use all of the different fields in each label, possibly even more. However when it is being typed each time, one field per label is sufficient. It would be annoying, at least to me, to have to move to a different field a bunch of times within one label.

Three Columns, not Five
Consider modifying the layout to eliminate the separator columns. They are put there automatically, but they are unnecessary and in an unprotected format they interefere because a tab will stop in one of those separator columns even though you don't want anyone typing there. Instead have three columns with the indents for the columns where they currently are on the page. It is the indents, rather than the column boundaries that hold your text in place. Again, for mail merge I would not care about the extra columns.

Use of the Classic File New Dialog encourages use of custom templates because it makes using them easier
It makes it easier to find them when they are stored in the User Templates folder or the shared Workgroup Templates folder. It also makes it harder to open a template by mistake. It is fairly simple to make this dialog the easiest way to start a new document avoiding Microsoft's online templates that are not designed for your business. 2007 Add to QAT - File New Variations in the Versions of Word

Hope this helps.