Clear and Add items to a DataGridViewComboBox but only for the selected row, not the entire column

Question

There are couple of posts on DataGridViewComboBox but they don't cover this specific case. I have a DGV in a shoe billing form, and the first three columns are comboboxes. The first, for Model; second, for Color; third, for Number. Since I want people to only sell what's in stock, in CellValueChanged; depending on the ColumnIndex I clear the next combo and insert the corresponding Items. Quick example, I have "Nike Pegassus" in the first combo, I select "Green" on the second one, and I select all the available numbers for that model and color and insert those into third column, after I cleared items in there, in case there was another color selected. Here's part of the code

If e.RowIndex >= 0 Then
    If e.ColumnIndex = 0 Then
        Dim objColumna As DataGridViewComboBoxColumn = dtgDetalle.Columns(1)
        Dim colItems As New Collection
        Dim Dattabla As DataTable
        Dim objColor As New clsColor(objObjeto.Sesion)
        Dattabla = objColor.BuscarTodos("CodColor IN (select distinct Stock.CodColor from Stock inner join Color on Stock.CodColor = Color.CodColor where Stock.Cantidad > 0 AND Stock.CodModelo=" & CType(objColumna.Items(dtgDetalle.Rows(e.RowIndex).Cells(0).Value), clsElementoListaFactura).Codigo & ")")
        objColor = Nothing
        objColumna = dtgDetalle.Columns(1)
        objColumna.Items.Clear()
        dtgDetalle.Rows(e.RowIndex).Cells(1).Value = Nothing
        dtgDetalle.Rows(e.RowIndex).Cells(2).Value = Nothing

        For Each darRecord In Dattabla.Rows
            objColor = New clsColor(objObjeto.Sesion)
            objColor.Codigo = darRecord.item("CodColor").ToString
            Dim objElemento As New clsElementoListaFactura(darRecord.item("Color").ToString, objColumna.Items.Count, "C", CInt(darRecord.item("CodColor").ToString), "1")
            objColumna.Items.Add(objElemento)
            objColor = Nothing
        Next

        objColumna.ValueMember = "ItemData"
        objColumna.DisplayMember = "Name"

. . . . . .

That works just fine for only one row! When I go to row #2 and change the index of the first combo, I want only to Combos (1, 1) and (1, 2) to be altered, but I get also (0, 1) and (0, 2) cleared and with the new values inserted. What would be the best way for me to clear the items of a specific row within a column, and then insert items only in that cell? If I'm not being clear, please ask. This is really starting to become a pain. Thanks!