keep datagridview old results after new search

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VB

Hello,
I have a datagridview which I fill with values from SQL Server table after a search with sqldataadapter, my problem is that I want to keep older rows in datagridview after a NEW search, now it deletes old results, I have bind the grid to a dataset, here is the code :

SqlConnection2.Open()
     SqlDataAdapter7.SelectCommand.Parameters(0).Value = TextBox1.Text
       SqlDataAdapter7.Fill(DataSet91, "phones")
       Dim dt1 As DataTable = DataSet91.Tables.Item("phones")
       Dim rowCustomer1 As DataRow
       For Each rowCustomer1 In dt1.Rows

         MessageBox.Show("Το Νουμερο τηλεφωνου " + rowCustomer1.Item("telephone").ToString + " κινητο " + rowCustomer1.Item("mobile").ToString, "τηλεφωνα", MessageBoxButtons.OK)
             Next

       SqlConnection2.Close()

       SqlConnection2.Open()

      Dim rowCustomer12 As DataRow

       If TextBox6.TextLength <> 0 Then
          SqlDataAdapter7.SelectCommand.Parameters(0).Value = TextBox6.Text
           SqlDataAdapter7.Fill(DataSet91, "phones")
     For Each rowCustomer12 In dt1.Rows
MessageBox.Show("Το Νουμερο τηλεφωνου " + rowCustomer12.Item("telephone").ToString + " κινητο " + rowCustomer12.Item("mobile").ToString, "τηλεφωνα", MessageBoxButtons.OK)
                    Next


       End If
       SqlConnection2.Close()

it deletes rows even if I assign it's dataset to a NEW datatable