Word Object?

Hi guys i have a question about the word object model and how something can be accomplished with it. We have a system where i work at where word correspondence is sent through a reporting object. The reporting object just takes some SQL and the word document and prints the document with the merge fields named in the SQL. The problemw we have no is that we have to print certain correspondence where there is a header document and multiple linked documents associated with the main document that has the same merge field name. Ex ( for a claim we have to print up to say 5 beneficiaries ) so we have to reproduce the same document 5 times...the only difference being the name of the merge field. In document on say we would have {Benef1) and in document 5 we would have {benef5}. Which means we need to pass {benef1}....{benef5} when we pass the SQL. I have found that through vb i can change the values of the merge fields dynamically. The problem is we have no control over what goes into the reporting object. What i need is to associate a vb macro with the word document that changes the merge fields dynamically. This would need to happen each time we loop through the recordset..but i have not found any kind of event that could accomplish this. Anyone have any ideas how to do this?

thanks
ncage