I would use a Dictionary & Collection object to count how many are in each category in order to determine how you would update the extra fields column.
'Set reference to Microsoft Scripting Runtime
' (or use late-binding)
Dim myDict As Dictionary, col As Collection
Dim i As Long, v As Variant
Dim sKey As String
Dim rTable As Range
Dim vTable As Variant, vResults As Variant
'there are more robust methods of selecting the table range
'depending on your actual layout
'And code will also make a difference if the original range includes
' or does not include the "Extra Field" Column
' Code below assumes it is NOT included in original data
Set rTable = ThisWorkbook.Worksheets("sheet2").Cells(1, 1).CurrentRegion
vTable = rTable
Set myDict = New Dictionary
For i = 2 To UBound(vTable)
sKey = vTable(i, 1) & vTable(i, 2) & vTable(i, 3) & vTable(i, 4)
Set col = New Collection
If Not myDict.Exists(sKey) Then
col.Add Item:=WorksheetFunction.Index(vTable, i, 0)
myDict.Add Key:=sKey, Item:=col
myDict(sKey).Add Item:=WorksheetFunction.Index(vTable, i, 0)
For Each v In myDict.Keys
Select Case myDict(v).Count
Debug.Print v, "Do update for two rows"
Debug.Print v, "Do update for three rows"
Debug.Print v, "No update needed"
1234V22341212 Do update for three rows
1234v22351215 No update needed
2234v22361515 Do update for two rows
2234v22361311 No update needed
However, I would definitely use Power Query, which can simply group by the four columns and produce a count and is available in Windows Excel 2010+ and 365. Depending on that count, you can then create a new column.
It is impossible to provide any code for that purpose without understanding the specifics of your updating Extra Field and the differences between what occurs for 2, 3, 4,... the same.