To manually create a "legal blackline", follow these steps:

The following Word 2010 macro creates a blackline version from the existing document (the new document) and a selected document (which you will be prompted for). 

Note that you should add the following registry entry to resolve a Word bug concerning large table comparison: 

[HKEY_CURRENT_USER\Software\Microsoft\Office\14.0\Word\Options] "DocCompareLargeTables"=dword:00000001

Sub LegalBlackLine()

' Creates a Legal Blackline document from the current

' open document, and a selected previous version of the document.

' By Edward Chan (c) 2014

    Dim fOpen As FileDialog

    Dim OriginalDocument As String

    Dim RevisedDocument As String

    Dim ComparedDocument As Document

    RevisedDocument = ActiveDocument

    Set fOpen = Application.FileDialog(FileDialogType:=msoFileDialogOpen)

    fOpen.AllowMultiSelect = False  ' Don't allow multi-select.

    fOpen.Title = "Select the old version of the file"

    fOpen.InitialFileName = ActiveDocument.Path & "\Select Old File"

    If fOpen.Show = -1 Then  ' Selected a File

        OriginalDocument = fOpen.SelectedItems.Item(1)  ' Get the name of the Doc

    Else

    Exit Sub

    End If

    Documents.Open OriginalDocument, ReadOnly:=True

   Set ComparedDocument = Application.CompareDocuments( _

        OriginalDocument:=Documents(OriginalDocument), _

        RevisedDocument:=Documents(RevisedDocument), _

        Destination:=wdCompareDestinationNew, _

        Granularity:=wdGranularityWordLevel, _

        CompareFormatting:=False, _

        CompareCaseChanges:=True, _

        CompareWhitespace:=False, _

        CompareTables:=True, _

        CompareHeaders:=False, _

        CompareFootnotes:=True, _

        CompareTextboxes:=True, _

        CompareFields:=False, _

        CompareComments:=True, _

        CompareMoves:=True, _

        RevisedAuthor:="Changed to", _

        IgnoreAllComparisonWarnings:=False)

    Documents(OriginalDocument).Close

    Documents(ComparedDocument).Activate

'Change view to redline

    With Options

        .InsertedTextMark = wdInsertedTextMarkColorOnly

        .InsertedTextColor = wdBlue

        .DeletedTextMark = wdDeletedTextMarkStrikeThrough

        .DeletedTextColor = wdRed

        .RevisedPropertiesMark = wdRevisedPropertiesMarkNone

        .RevisedPropertiesColor = wdByAuthor

        .RevisedLinesMark = wdRevisedLinesMarkNone

        .CommentsColor = wdByAuthor

        .RevisionsBalloonPrintOrientation = wdBalloonPrintOrientationPreserve

    End With

    ActiveWindow.View.RevisionsMode = wdInLineRevisions

    With Options

        .MoveFromTextMark = wdMoveFromTextMarkHidden

        .MoveFromTextColor = wdAuto

        .MoveToTextMark = wdMoveToTextMarkColorOnly

        .MoveToTextColor = wdAuto

        .InsertedCellColor = wdCellColorNoHighlight

        .MergedCellColor = wdCellColorLightYellow

        .DeletedCellColor = wdCellColorPink

        .SplitCellColor = wdCellColorLightOrange

    End With

    With ActiveDocument

        .TrackMoves = True

        .TrackFormatting = True

    End With

End Sub

The following Word macro saves the current document as a PDF, with blackline markings on the left hand side for tracked changes.

'

' Show the blackline view and save as PDF.

' Edward Chan 2015-10-06

'

    With Options

        .InsertedTextMark = wdInsertedTextMarkNone

        .InsertedTextColor = wdRed

        .DeletedTextMark = wdDeletedTextMarkHidden

        .DeletedTextColor = wdByAuthor

        .RevisedPropertiesMark = wdRevisedPropertiesMarkNone

        .RevisedPropertiesColor = wdByAuthor

        .RevisedLinesMark = wdRevisedLinesMarkLeftBorder

        .RevisedLinesColor = wdAuto

        .CommentsColor = wdByAuthor

        .RevisionsBalloonPrintOrientation = wdBalloonPrintOrientationPreserve

    End With

    ActiveWindow.View.RevisionsMode = wdInLineRevisions

    With Options

        .MoveFromTextMark = wdMoveFromTextMarkHidden

        .MoveFromTextColor = wdAuto

        .MoveToTextMark = wdMoveToTextMarkNone

        .MoveToTextColor = wdAuto

        .InsertedCellColor = wdCellColorNoHighlight

        .MergedCellColor = wdCellColorLightYellow

        .DeletedCellColor = wdCellColorPink

        .SplitCellColor = wdCellColorLightOrange

    End With

    With ActiveDocument

        .TrackMoves = True

        .TrackFormatting = False

    End With

    ActiveDocument.ExportAsFixedFormat OutputFileName:= _

        Replace(ActiveDocument.FullName, ".docx", ".pdf"), _

        ExportFormat:=wdExportFormatPDF, OpenAfterExport:=True, OptimizeFor:= _

        wdExportOptimizeForPrint, Range:=wdExportAllDocument, From:=1, To:=1, _

        Item:=wdExportDocumentWithMarkup, IncludeDocProps:=True, KeepIRM:=True, _

        CreateBookmarks:=wdExportCreateHeadingBookmarks, DocStructureTags:=True, _

        BitmapMissingFonts:=True, UseISO19005_1:=False

End Sub

Redline and PDF

In a similar fashion, here is a macro that will create redlines and blue additions:

Note that you should add the following registry entry to resolve a Word bug concerning large table comparison: 

[HKEY_CURRENT_USER\Software\Microsoft\Office\14.0\Word\Options] "DocCompareLargeTables"=dword:00000001 

Sub RedLineAndPDF()

'

' Show the redline view and save as PDF.

' Edward Chan 2022-06-29

'

 Dim outputName As String

'Change view to redline

    With Options

        .InsertedTextMark = wdInsertedTextMarkColorOnly

        .InsertedTextColor = wdBlue

        .DeletedTextMark = wdDeletedTextMarkStrikeThrough

        .DeletedTextColor = wdRed

        .RevisedPropertiesMark = wdRevisedPropertiesMarkNone

        .RevisedPropertiesColor = wdByAuthor

        .RevisedLinesMark = wdRevisedLinesMarkNone

        .CommentsColor = wdByAuthor

        .RevisionsBalloonPrintOrientation = wdBalloonPrintOrientationPreserve

    End With

    ActiveWindow.View.RevisionsMode = wdInLineRevisions

    With Options

        .MoveFromTextMark = wdMoveFromTextMarkHidden

        .MoveFromTextColor = wdAuto

        .MoveToTextMark = wdMoveToTextMarkColorOnly

        .MoveToTextColor = wdAuto

        .InsertedCellColor = wdCellColorNoHighlight

        .MergedCellColor = wdCellColorLightYellow

        .DeletedCellColor = wdCellColorPink

        .SplitCellColor = wdCellColorLightOrange

    End With

    With ActiveDocument

        .TrackMoves = True

        .TrackFormatting = True

    End With

' Save doc

    ActiveDocument.ExportAsFixedFormat OutputFileName:= _

        Left(ActiveDocument.FullName, InStrRev(ActiveDocument.FullName, ".")) & "pdf", _

        ExportFormat:=wdExportFormatPDF, OpenAfterExport:=True, OptimizeFor:= _

        wdExportOptimizeForPrint, Range:=wdExportAllDocument, From:=1, To:=1, _

        Item:=wdExportDocumentWithMarkup, IncludeDocProps:=True, KeepIRM:=True, _

        CreateBookmarks:=wdExportCreateHeadingBookmarks, DocStructureTags:=True, _

        BitmapMissingFonts:=True, UseISO19005_1:=False

End Sub