Private Sub AddNodes(trv As TreeView, ParamArray txt() As String)
 
        Dim trn As TreeNode = trv.Nodes.Add(txt(0))
        For i As Integer = 1 To txt.Length - 1
            trn.Nodes.Add(txt(i))
        Next i
    End Sub

    AddNodes(trv, "ax", "cd", "fh")
    AddNodes(trv, "ax2", "cd2", "fh2", "ex")

 Private Sub AddNodes2(trv As TreeView, ParamArray txt() As String)
 
     Dim trn As TreeNode = trv.Nodes(0)
     Dim trn_sub As TreeNode = trn.Nodes.Add(txt(0))
     For i As Integer = 1 To txt.Length - 1
         trn_sub.Nodes.Add(txt(i))
     Next i
 End Sub

    trv.Nodes.Add("base")
    AddNodes2(trv, "ax", "cd", "fh")
    AddNodes2(trv, "ax2", "cd2", "fh2", "ex")