A family of Microsoft word processing software products for creating web, email, and print documents.
I'm not clear what your text about VBA has to do with your need to prevent a template from being over-written.
Templates don't get over-written unless someone opens the template itself to edit it in Word. The default action for templates when they are double-clicked is to spawn a document, the template does not get opened.
You can reduce the likelihood of a template being edited by placing it in a user's Custom Office Templates folder so they can access it via Word's File>New command.
You can also create a Workgroup Templates folder on a network share, then users create a document by choosing File>New>Custom (or Personal) and selecting a template from which to create a document. This approach makes it very unlikely a template will accidentally be over-written. Here's my article with more details: Shared Workgroup Templates - Best Practices