1. Once you have set up the data source in the Word document, Word should
not forget it (whatever it is) - in the case of an Excel document it should
remember everything it needs to know - sheet, selection criteria, and
sequence criteria.

2. However, if you need to do the OpenDataSource or modify the Sheet in your
macro, things are slightly different. Typically, if you macro record the
process of connecting to a data source, Word will record an OpenDataSource
method call. During initial connection you don't usually get an opportunity
to select anything except the sheet or a named range (unless you go through
MS Query, which is a different subject). In the recorded macro you will
probably see that WOrd records the SQLStatement parameter of the
OpenDataSource call as something like

"SELECT * FROM `Sheet1$`"

If you then use Edit Recipients to filter and sequence the data, Word may do
two things:
a. if you select/deselct individual rows, Word actually stores information
internally about the rows. This is a highly unpredictable process for a
number of reasons - what, for example, if you sort the data source in Excel.
How is Word supposed to identify which row you meant when you checked its
box? If you disconnect the data source, as far as I know, Word will lose any
information about which rows were selected anyway. So avoid that.
b. it may generate a new SQL statement from your criteria and assign it to

ActiveDocument.MailMerge.DataSource.QueryString

So, as long as you do not allow the query criteria to be changed, you should
be able to print the value of that property (e.g. in the Immediate Window in
the VBA Editor, and use it either in your own OpenDataSource call or in just
the same way WOrd does it, i.e. by setting that .QueryString property.

However, if you want people to be able to modify the query, the problem is
that you then have to generate the necessary SQL programmatically, and
although I suspect it's not that hard, there are potentially a number of
gotchas.

What I suggest is that
a. you try to ensure that the Word document is not connected to any data
source before you open it (otherwise, Word will /always/ look for that
source before you can do anything, even in VBA)
b. you make the connection in Word using OpenDataSource. Word inserts a lot
of parameters in this call, but most of them do nothing. In this case you
can probably get away with just the Name and SQLStatement parameters, e.g.

objDocument.MailMerge.OpenDataSource _
 Name:="the full path name of your Excel workbook", _
 SQLStatement:="the SELECT statement you got from .Querystring"

I suspect that might be rather confusing but try macro recording a new
connection, and have a look at that .Querystring value.

Peter Jamieson