'aufruf nach einfügen des ds
Form1.InstForm1.tvw_grab.BeginUpdate()
    grb.fill_tvwgrab(InstForm1)
Form1.InstForm1.tvw_grab.EndUpdate()

Public Sub fill_tvwgrab(ByVal InstForm1)
        Dim str1, str11 As String
        Dim a As New TreeNode
        Dim a1 As New TreeNode
        Dim a2 As New TreeNode
        For Each dr As DataRow In tabgrab.Rows
            f_nx = dr(0)
            r_nrx = dr(1)
            gidx = dr(3)
            nidx = dr(4)
            nida = CInt(nid)
            maxbx = dr(5)
            maxba = CInt(maxbx)
            istbx = dr(6)
            istba = CInt(istbx)
            T1 = New Grab_TreeNode(f_n, r_nr, g_nr, gid, nid, maxb, istb)
            T1.Text = f_nx
            If f_n <> f_nx Then
                Form1.InstForm1.tvw_grab.Nodes.Add(T1)
            End If
            f_n = f_nx
            r_nr = r_nrx
            g_nr = g_nra
            gid = gidx
            nid = nida
            maxb = maxba
            istb = istba
            For Each dr1 As DataRow In tabgrab1.Rows
                f_nx1 = dr(0)
                r_nrx1 = dr(1)
                gidx1 = dr(3)
                nidx1 = dr(4)
                nidb = CInt(nidx1)
                maxbx1 = dr(5)
                maxbb = CInt(maxbx1)
                istbx1 = dr(6)
                istbb = CInt(istbx1)
                T2 = New Grab_TreeNode(f_n, r_nr, g_nr, gid, nid, maxb, istb)
                T2.Text = r_nrx
                If r_nrx1 <> r_nr1 Then
                    T1.Nodes.Add(T2)
                End If
                f_n1 = f_nx1
                r_nr1 = r_nrx1
                g_nr1 = g_nrb
                gid1 = gidx1
                nid1 = nidb
                maxb1 = maxbb
                istb1 = istbb
                For Each dr2 As DataRow In tabgrab2.Rows
                    f_nx2 = dr2(0)
                    r_nrx2 = dr2(1)
                    gidx2 = dr2(3)
                    nidx2 = dr2(4)
                    nidc = CInt(nidx2)
                    maxbx2 = dr2(5)
                    maxbc = CInt(maxbx2)
                    istbx2 = dr2(6)
                    istbc = CInt(istbx2)
                    T3 = New Grab_TreeNode(f_n, r_nr, g_nr, gid, nid, maxb, _
                      istb)
                    T3.Text = gidx2
                    If gid2 <> gidx2 Then
                        T2.Nodes.Add(T3)
                    End If
                    f_n2 = f_nx2
                    r_nr2 = r_nrx2
                    g_nr2 = g_nrx2
                    gid2 = gidx2
                    nid2 = nidx2
                    maxb2 = maxbx2
                    istb2 = istbx2
                    i = T3.Index
                    Form1.InstForm1.Label20.Text = i.ToString
                Next
            Next
        Next
    End Sub