ItemIndex of add events

[Matt]

I created a datagrid with a footer that used to add a row. This worked
for my other datagrids but this datagrid had two columns with
dropdownlists in the footer. The first dropdownlist is supposed to
trigger a change to the contents of the second dropdownlist.

This works fine with an edit because I have EditItemIndex. But with an
add I can't figure out how to get the right index. Here's what the
logic looks like, I have one subroutine to handle the various
dropdownlist changes:

Protected Sub ddlTest_SelectedIndexChanged(ByVal sender As Object,
ByVal e As System.EventArgs)
Dim ddl As DropDownList = CType(sender, DropDownList)
Dim aSqlParams As Array =
Array.CreateInstance(GetType(SqlParameter), 1)
Dim sName As String = ddl.ID

Select Case sName
Case "ddlOneAdd"
'???
Case "ddlOneEdit"
aSqlParams.SetValue(New SqlParameter("@catid",
ddl.SelectedItem.Value), 0)
ddl =
grdAllocation.Items(grdTest.EditItemIndex).Cells(1).FindControl("ddlTwoEdit")
BindDropDownList(ddl, "sp_name", "value", "text",
aSqlParams)
End Select
End Sub

As I said, the Edit routine works because I can use
grdTest.EditItemIndex to do my FindControl to get to the second
dropdownlist.

How can I get the correct index when the rows are in the footer and
there isn't any corresponding index value to retrieve?