With the following macro (copied from this usenet, modified & working
thank you) is there a way the row number (in this example 771) updates
automatically when I manually add rows between 3 & 771.

******************
Dim rng As Range, i As Long
Dim lastrow As Long
With Worksheets("Sheet1")
Set rng = .Range(.Cells(3, 2), .Cells(771, 2).End(xlUp))
End With
With Worksheets("Sheet3")
lastrow = .Cells(Rows.Count, 1).End(xlUp).Row
For i = lastrow To 1 Step -1
If Application.CountIf(rng, .Cells(i, 1)) < 0 Then
.Rows(i).Delete
End If
Next i
End With
*********************

TIA

Ron