I think your main choices are:
a. do not use mail merge. Always start from the initial document, then for
each record in your data source
 - copy/paste the initial document into an intermediate document
 - insert your data and pictures into the intermediate document
 - copy the intermediate document and append it to the output document
 - clear or delte the intermediate document
b. use mail merge.
 - create a new data source from the data in your VB6 program
 - use OpenDataSource to connect the initial document to that data source
 - perform the merge
 - do any necessary postprocessing on the output document (which is the
ActiveDocument after the merge.

Before you use (b), you need to check that mailmerge is a viable process for
producing the kind of documents you want from the inputs you have. For
example, Mailmerge is not designed to process Parent/child tables to produce
things such as "one invoice with detail lines per customer". If you write
your own merge function, you may get a lot more control, but you have to do
a lot more work, e.g.
 - decide how users should define where data should go in their documents
 - validate that user markup
 - do all the data insertion
 - consider what to do about stuff such as headers/footers, other types of
field codes the users might enter (at what point should they be
executed/resolved)

Peter Jamieson
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