RobiNew, here you are, enjoy it!
Code:
Sub OneLiners()
'In selection, replace Chr(13) with Chr(11) between all consecutive one-line paras.
Dim oRng
Application.ScreenUpdating = False
Set oRng = selection.range
For Each Para In oRng.Paragraphs
If Para.range.End >= oRng.End Then Exit Sub
If Para.range.ComputeStatistics(wdStatisticLines) = 1 And _
Para.Next.range.ComputeStatistics(wdStatisticLines) = 1 Then
Para.range.Characters.Last.text = Chr(11)
Do While Para.Next.range.ComputeStatistics(wdStatisticLines) = 1
Para.range.Characters.Last.text = Chr(11)
Loop
End If
Next
Application.ScreenUpdating = True
Set oRng = Nothing
End Sub