Use the CellMerge property to combine two or more cells in the same item in a single cell. The data of the source cell is displayed in the new larger cell. All the other cells' data is not lost. Use the ItemDivider property to display a single cell in the entire item ( merging all cells in the same item ). Use the UnmergeCells method to unmerge the merged cells. Use the CellMerge property to unmerge a single cell. Use the MergeCells method to combine one or more cells in a single cell. Use the Add method to add new columns to the control. Use the SplitCell property to split a cell.

You can merge the first three cells in the root item using any of the following methods:

•  With Tree1
      With .Items
          .CellMerge(.RootItem(0), 0) = Array(1, 2)
      End With
  End With

• With Tree1
      .BeginUpdate
      With .Items
          Dim r As Long
          r = .RootItem(0)
          .CellMerge(r, 0) = 1
          .CellMerge(r, 0) = 2
      End With
      .EndUpdate
  End With

• With Tree1
      .BeginUpdate
      With .Items
          Dim r As Long
          r = .RootItem(0)
          .MergeCells .ItemCell(r, 0), .ItemCell(r, 1)
          .MergeCells .ItemCell(r, 0), .ItemCell(r, 2)
      End With
      .EndUpdate
  End With

• With Tree1
      With .Items
          Dim r As Long
          r = .RootItem(0)
          .MergeCells .ItemCell(r, 0), Array(.ItemCell(r, 1), .ItemCell(r, 2))
      End With
  End With

• With Tree1
      With .Items
          Dim r As Long
          r = .RootItem(0)
          .MergeCells Array(.ItemCell(r, 0), .ItemCell(r, 1), .ItemCell(r, 2))
      End With
  End With

The following sample shows few methods to unmerge cells: 

• With Tree1
      With .Items
          .UnmergeCells .ItemCell(.RootItem(0), 0)
      End With
  End With

• With Tree1
      With .Items
          Dim r As Long
          r = .RootItem(0)
          .UnmergeCells Array(.ItemCell(r, 0), .ItemCell(r, 1))
      End With
  End With

• With Tree1
      .BeginUpdate
      With .Items
          .CellMerge(.RootItem(0), 0) = -1
          .CellMerge(.RootItem(0), 1) = -1
          .CellMerge(.RootItem(0), 2) = -1
      End With
      .EndUpdate
  End With

The following VB sample merges the first three cells in the focused item:

With Tree1.Items
    .CellMerge(.FocusItem, 0) = 1
    .CellMerge(.FocusItem, 0) = 2
End With

The following C++ sample merges the first three cells in the focused item:

#include "Items.h"
CItems items = m_tree.GetItems();
COleVariant vtItem( items.GetFocusItem() ), vtColumn( long( 0 ) );
items.SetCellMerge( vtItem, vtColumn, COleVariant( long(1) ) );
items.SetCellMerge( vtItem, vtColumn, COleVariant( long(2) ) );

The following VB.NET sample merges the first three cells in the focused item:

With AxTree1.Items
    .CellMerge(.FocusItem, 0) = 1
    .CellMerge(.FocusItem, 0) = 2
End With

The following C# sample merges the first three cells in the focused item:

axTree1.Items.set_CellMerge(axTree1.Items.FocusItem, 0, 1);
axTree1.Items.set_CellMerge(axTree1.Items.FocusItem, 0, 2);

The following VFP sample merges the first three cells in the focused item:

with thisform.Tree1.Items
	.DefaultItem = .FocusItem
	.CellMerge(0,0) = 1
	.CellMerge(0,0) = 2
endwith

In other words, the sample shows how to display the first cell using the space occupied by three cells.