When you insert a comment into a worksheet, that comment is associated with a single cell. There may be times when you want to have a single comment associated with two or more cells. Unfortunately, Excel doesn't provide this capability—there is a strict one-to-one correspondence between comments and cells.

You can, however, use a workaround—create your own comments. You can do this using a text box to contain your comment, and then draw lines between the text box and whatever cells the comment applies to. If you normally want your comments hidden, then you will need to use a macro that takes care of making the text box and lines visible or invisible.

For instance, assume that you create a comment in a text box named Text Box 1. Further, assume that you have two lines leading from the text box to the cells to which the comment applies. The first line, named Line 1, leads to cell C15. The second line, named Line 2, leads to cell F7. You could add the following macro to the worksheet's object:

Private Sub Worksheet_SelectionChange(ByVal Target As Excel.Range)
    Shapes("Text Box 1").Visible = False
    Shapes("Line 1").Visible = False
    Shapes("Line 2").Visible = False

    If Target.Address = "$C$15" Then
        Shapes("Text Box 1").Visible = True
        Shapes("Line 1").Visible = True
    End If
    If Target.Address = "$F$7" Then
        Shapes("Text Box 1").Visible = True
        Shapes("Line 2").Visible = True
    End If
End Sub

Anytime a selection is made on the worksheet, the three objects are hidden. If cell C15 is selected, the textbox and the line appropriate line are made visible. Similarly, if cell F7 is selected, the textbox and its line are made visible.