I am not really clear on what you are requesting.
But you can use the QueryCellStyleInfo to conditionally adjust style properties on cells. For example, here is code that you can use in the QueryCellStyleInfo event to hide the +/- on records that have no children.
// Prevent the +/- Icon for an empty row
if (e.TableCellIdentity.TableCellType == GridTableCellType.RecordPlusMinusCell)
{
Record r = e.TableCellIdentity.DisplayElement.ParentRecord as Record;
if (r != null && r.ParentTable.TableDescriptor.Name != DataSetBuilder.SALESTRANSACTION_LIST
&& r.NestedTables.Count > 0 && r.NestedTables[0].ChildTable.GetFilteredRecordCount() == 0)
{
e.Style.CellType = "Static";
}
}