merge documents

[Russ]

I am trying to do combine seperate documents that are each mailmerged. they
are each mail merged, using the same primary key. each document has a
seperate section of the main document, and may or may not be included in the
master document. how do i merge these smaller documents into the larger one.
they must still retain there merged values. the documents must also match
based on the primary key.

thanks