How to Run VBA Macro in Word Doc after being Merged by external application

We are using the XML or Word ML format from Office 2003.

How do I get a macro to run after a MS Word ML document has been merged by another application (not Word) called SIMS by Capit开发者_如何学编程a.

How can I get the Macro to run after a merge, when the document is being previewed?

The Word-document doesn't know that it has been merged by another application. The only way that comes to my mind is to check for changes when the doc is opened and then run your macro.