Well, you could try the following VBA as a starting point, but I think it will need some work. It assumes that your breaks are always going to be after a space (not unreasonable for a schema IMO) so if you have spaceless text longer than a line you might still have to break those by hand.
This replaces final spaces by the return symbol in the current font + a no-width breaking space, so as long as you can adjust the width of the return symbol (there are various possible ways to do that) so that Word still wraps at the same points, it may be enough.
Sub markAutoLineBreaks()
' Changes line breaks automatically made by Word
' into "return" charaters, but only where the line
' ends in a " "
' This operates on the text in the current selection
' We use a character style
Const strStyleName As String = "contchar"
Dim r As Word.Range
Dim styContchar As Word.Style
' Add the style if it is not present
On Error Resume Next
Set styContchar = ActiveDocument.Styles.Add(strStyleName, Type:=WdStyleType.wdStyleTypeCharacter)
Err.Clear
On Error GoTo 0
' Set the characteristics of the style. What you need to aim for
' is to adjust the character width so that the text breaks at the
' same point (if possible)
Set styContchar = ActiveDocument.Styles(strStyleName)
With styContchar.Font
.Size = 8
End With
' Save the selection
Set r = Selection.Range
' remove old line end marks
With Selection.Find
.ClearFormatting
.Style = styContchar
.Replacement.ClearFormatting
' Not sure what to use here, but this will have to do
.Replacement.Style = ActiveDocument.Styles("Default Paragraph Font")
' 9166 is the return character. 8204 is a No-width breaking space
.Text = ChrW(9166) & ChrW(8204)
.Replacement.Text = " "
.Forward = True
.Format = True
.MatchCase = False
.MatchWholeWord = False
.MatchWildcards = False
.MatchSoundsLike = False
.MatchAllWordForms = False
End With
Selection.Find.Execute Replace:=wdReplaceAll
' Moving down lines is not completely straightforward
' but this seems to work
Selection.Collapse direction:=wdCollapseStart
Do Until Selection.End > r.End
Selection.Bookmarks("\line").Select
If Right(Selection, 1) = " " Then
Selection.SetRange Selection.End - 1, Selection.End
Selection.Delete
Selection.Text = ChrW(9166) & ChrW(8204)
Selection.Style = styContchar
Selection.Bookmarks("\line").Select
Selection.Collapse direction:=wdCollapseStart
End If
Selection.MoveDown wdLine, 1, False
Loop
' reselect our original selection
r.Select
Set r = Nothing
End Sub