Formview Inserting new detail record - DataKey field ID not avail

[Jawahar]

All,
I have a form view that allows edit (updates) and Inserts (Add a new detail
row) .
THe formview is populated via a SqlDatasource that is fitered by value that
is passed to the SqlDatasource Filter expression.

When try to add a new detail record for the ID passed to the Filter
Expression I am not able to get it initial ID value (which is the DataKey for
the FormView).
For example CustomerID say 123 has three orders now I want to add a new
order to CustomerID 123.

In insert mode all the filed Textboxes are empty (as they should be) but
even the CustomerID field, even though it is bound to CustomerID when the
form first loads.
Currently I keeping the currentily selected CustomerID in a ViewState field
to reference it later when doing the insert (an insert into the Orders table
where I need to have a the CustomerID)
There must be an eaiser way to do this than use the ViewState.

This works fine for updates the CustomerID is avialble in the field in the
Update mode.

Does anyone know a way to get the CustomerID and populate it to the
CustomerID field in Insert mode hence be able to pass it along as the
CustomerID insert parameter.

Any help is appreciated.
Jawahar