I miss grouping functionality in VirtualGrid. In my opinion, the following process would be conceivable:
1. user interaction triggers an event - e. g. GroupChanged (similar to FilterChanged).
2. This event determines all available groups and returns them to the VirtualGrid. 
3. if the user expand a group > a second event is fired - and returns all matching data rows.

Scenario to cover: the user tries to filter the grid not with each entered symbol but when the value in the filter cell is committed (Enter key is pressed) and the editor is closed. The CellValuePushed event is fired only for data cells and the FilterChanged event is fired with each keystroke but not when the editor is closed. A similar scenario is valid for the new row. There is no suitable event for capturing when a certain cell is updated in the new row as well.

Using RadVirtualGrid, I have a requirement for showing hierarchical levels of data. The parent level and child levels share the SAME column headers.  I am utilizing the QueryHasChildRows event of the grid to set the number of rows for each hierarchical level. In that event I set a few properties to control how a child view is rendered as below:

            else if (e.ViewInfo.HierarchyLevel > 0)
            {
                var items = ((IList<AllocStructNode>)e.ViewInfo.ParentViewInfo.Tag)[e.ViewInfo.ParentRowIndex];
                if (items.Children != null && items.Children.Count > 0)
                {
                    e.ViewInfo.Tag = items.Children;
                    e.ViewInfo.RowCount = items.Children.Count;
                    e.ViewInfo.HeaderRowHeight = 0;
                    e.ViewInfo.ShowHeaderRow = false;
                    e.ViewInfo.FilterRowHeight = 0;
                    e.ViewInfo.ShowFilterRow = false;
                    e.ViewInfo.Padding = new Padding(0);
                    e.ViewInfo.HorizontalScrollState = ScrollState.AlwaysHide;
                }
            }


When a new level is rendered, a new demarcated section of child table element with its own horizontal scrolling displayed. When the parent is horizontally scrolled, the child level doesn't scroll (not synchronized). Similarly, when the child is horizontally scrolled, the parent does not scroll as well.

Workaround:
See attached project.