You should be able to edit the Author names for the original using code like:
Code:
Sub DemoA()
Dim Cmnt As Comment
For Each Cmnt In ActiveDocument.Comments
Cmnt.Author = "Internal"
Next
End Sub
I'm not sure if this still works in Office 2016, though. If it does, you might also try running the following macro from the original document.
Code:
Sub DemoB()
Application.ScreenUpdating = False
Dim DocSrc As Document, DocTgt As Document
Dim i As Long, j As Long
Set DocSrc = ActiveDocument
With Dialogs(wdDialogFileOpen)
If .Display Then
Set DocTgt = Documents.Open(FileName:=.Name, _
AddToRecentFiles:=False, Visible:=True)
End If
End With
If DocTgt Is Nothing Then Exit Sub
With DocTgt
For j = i To .Comments.Count
.Comments(j).Author = "External"
Next
End With
With DocSrc
For i = 1 To .Comments.Count
With DocTgt
For j = i To .Comments.Count
With .Comments(j)
If .Scope.Text = DocSrc.Comments(i).Scope.Text Then
If .Range.Text = DocSrc.Comments(i).Range.Text Then
.Author = "Internal"
Exit For
End If
End If
End With
Next
End With
Next
End With
'cleanup
Set DocTgt = Nothing: Set DocSrc = Nothing
Application.ScreenUpdating = True
End Sub
Do note that, if the external reviewers have edited the actual text a comment applies to, or have edited a comment, the above code won't recognise your 'Internal' comments as being such.