Put this into a standard module.
The basic process is
1. Create a range from Col A (change it to suit) of all the cells that have a constant text data in them. Get out if there are none
2. Look at each of the cells from 1) for IN, or IN ,
3. Add ,MI if 2) is in the cell
Check online help for the details of the statements, or post a question
Good luck
Option Explicit
Sub AddMI()
Dim rSearch As Range, rCell As Range
Set rSearch = Nothing
On Error Resume Next
Set rSearch = Worksheets("Sheet1").Range("A:A").SpecialCells(xlCellTypeConstants, xlTextValues)
On Error GoTo 0
If rSearch Is Nothing Then Exit Sub
Application.ScreenUpdating = False
For Each rCell In rSearch.Cells
If InStr(1, rCell.Value, "IN,", vbTextCompare) > 0 Then
rCell.Value = rCell.Value & ",MI"
ElseIf InStr(1, rCell.Value, "IN ,", vbTextCompare) > 0 Then
rCell.Value = rCell.Value & ",MI"
End If
Next
Application.ScreenUpdating = True
MsgBox "All Done"
End Sub
If (when) you need to update it, the changes should be pretty easy for you to figure out -- just follow the basic approach
Paul