A macro may do it.
As an alternative, I think an ASK field would do what you want, but it really depends on the who the "End User" is for this form. An ASK field stores input in a bookmark. A REF field displays the ASK bookmark. So you can ASK for User Name, then insert a REF field that displays the User Name bookmark in as many places in the document as you want.
Do you intend to use FORM fields and lock down your form? If so, getting the ASK field updated will be a bit tricky.
I've created a very simple form that uses an ASK field for "Applicant Name", REF fields to display the ASK field bookmark in two places, and FORM fields for "Address" and "Ownership Type".
I've uploaded the Word document at http://lindagail.gee...om/formtest.doc
and an example showing the form with and without the Field Codes at http://lindagail.gee...om/wordform.png
If this is anywhere near what you need, please post back and I can answer more specific questions.