Inserting another document into Word doc with vb.net

Hello

I am creating Word documents via Vb.net, adding the name and address details from a contact database automatically.  I now need to be able to insert another document.  My existing code is:-

  Dim oWord As Object

        Dim oDoc As Object
        Dim oPara1 As Object




        Dim objDoc As Object
        Dim objDocs As Object
        Dim range As Object

        oWord = CreateObject("Word.Application")
        objDocs = oWord.Documents
        '  oDoc = objDocs.Add("c:\data\mytemplate.doct")
        oDoc = objDocs.Add

        oDoc.Paragraphs.SpaceAfter = 0

        oDoc.Paragraphs.SpaceBefore = 0

        oWord.Visible = True

        oPara1 = oDoc.Content.Paragraphs.Add
        '  oPara1.Style = oDoc.Styles("No Spacing")
        oPara1.Range.Text = Trim(cmbTitle.Text) & " " & txtForename.Text.Substring(0, 1) & " " & txtSurname.Text & vbCrLf & Trim(txtContactAddress.Text) & vbCrLf & Trim(cmbContactTown.Text) & vbCr & Trim(cmbContactCounty.Text) & " " & Group.FGPostcode & vbCrLf


        '    oPara1.Range.Font.Name = "Calibri"
        oPara1.Range.Font.Bold = False
        '   oPara1.Format.SpaceAfter = 0
        oPara1.Range.InsertParagraphAfter()


        oPara1 = oDoc.Content.Paragraphs.Add
        oPara1.Range.Text = "Dear " & txtSalutation.Text & vbCrLf
        '    oPara1.Range.Font.Name = "Calibri"
        oPara1.Range.Font.Bold = False

       

        oDoc.Content.InsertFile("C:\data\myadd.doc")


        oDoc.SaveAs(SaveFile.FileName)


However if I use this all the text in the document is replaced by the contents of "C:\data\myadd.doc" rather than the text being added at the end of the name and address details.

Thanks