Here is how I accomplished it for what it is worth...

 Notice in "GetStructureFieldLayout" where I hide the label given a specifc layout.

Rod

 void theDataGrid_AssigningFieldLayoutToItem(object sender, AssigningFieldLayoutToItemEventArgs e)
        {
           
            if (((DataRowView)(e.Item)).Row["parent_id"].ToString().Length == 0)
            {
                if (theDataGrid.FieldLayouts.Exists("ParentLayout"))
                {
                    e.FieldLayout = theDataGrid.FieldLayouts["ParentLayout"];
                }
                else
                {
                    theDataGrid.FieldLayouts.Add(GetStructureFieldLayout("ParentLayout"));
                    e.FieldLayout = theDataGrid.FieldLayouts["ParentLayout"];

                    //If this item has a product_id value, then the record should not be editable.
                    //If the item does not have a product_id value, then AllowEdit on the
                    //model_id, part_id, and quantity cells.
                }
                               
            }
            else
            {
                if (theDataGrid.FieldLayouts.Exists("ChildLayout"))
                {
                    e.FieldLayout = theDataGrid.FieldLayouts["ChildLayout"];
                }
                else
                {
                    theDataGrid.FieldLayouts.Add(GetStructureFieldLayout("ChildLayout"));
                    e.FieldLayout = theDataGrid.FieldLayouts["ChildLayout"];

                    //If this item has a product_id value, then the record should not be editable.
                    //If the item does not have a product_id value, then AllowEdit on the
                    //model_id, part_id, and quantity cells.
                }
            }
        }       

private FieldLayout GetStructureFieldLayout(string keyName)
        {
            FieldLayout fl = new FieldLayout();

            fl.Key = keyName;
            if (keyName == "ChildLayout")
                fl.Settings.LabelLocation = LabelLocation.Hidden;

            Field fld = new Field();
            fld.Name = "model_id";
            fld.Settings.CellValuePresenterStyle = Application.Current.FindResource("leftBorderHyperlinkCell") as Style;           
            fld.Label = "Model ID";
            fld.Settings.CellMinWidth = 150.0;
            fld.Settings.AllowEdit = false;
            fl.Fields.Add(fld);

            fld = new Field();
            fld.Name = "part_id";           
            fld.Settings.CellValuePresenterStyle = Application.Current.FindResource("hyperlinkCell") as Style;           
            fld.Label = "Part ID";
            fld.Settings.CellMinWidth = 100.0;
            fld.Settings.AllowEdit = false;
            fl.Fields.Add(fld);

            fld = new Field();
            fld.Name = "serial_id";
            fld.Settings.CellValuePresenterStyle = Application.Current.FindResource("cellValuePresenter") as Style;
            fld.Label = "Serial ID";
            fld.Settings.CellMinWidth = 100.0;
            fld.Settings.AllowEdit = false;
            fl.Fields.Add(fld);

            fld = new Field();
            fld.Name = "product_id";
            fld.Settings.CellValuePresenterStyle = Application.Current.FindResource("hyperlinkCell") as Style;           
            fld.Label = "Product ID";
            fld.Settings.CellMinWidth = 100.0;
            fld.Settings.AllowEdit = false;
            fl.Fields.Add(fld);

            fld = new Field();
            fld.Name = "quantity";
            fld.Settings.CellValuePresenterStyle = Application.Current.FindResource("cellValuePresenter") as Style;
            fld.Label = "Quantity";
            fld.Settings.AllowEdit = false;
            fl.Fields.Add(fld);

            //The following four fields are needed to show the hierarchy in the grid.
            fld = new Field();
            fld.Name = "PRODUCT_STRUCTURE_NEST";
            fl.Fields.Add(fld);

            fld = new Field();
            fld.Name = "product_structure_id";
            fld.Visibility = Visibility.Hidden;
            fl.Fields.Add(fld);

            fld = new Field();
            fld.Name = "parent_id";
            fld.Visibility = Visibility.Hidden;
            fl.Fields.Add(fld);

            fld = new Field();
            fld.Name = "sequence";
            fld.Visibility = Visibility.Hidden;
            fl.Fields.Add(fld);           

            return fl;
        }