customer, the order display must be updated to show that customer's orders.&nbsp; As the user selects an order, the item display must be updated to show that order's line items.&nbsp; The synchronization is managed by a set of three DBFetchGroups, each with its own DBRecordList.&nbsp; The root DBFetchGroup manages data for the customer display.&nbsp; Subordinate to it, a second DBFetchGroup keeps the order display in step with the currently selected customer.&nbsp; And subordinate to that, a third DBFetchGr