Set rng = ActiveDocument.Range
    Do
        With rng.Find
            .ClearFormatting
            .Replacement.ClearFormatting
            .Forward = True
            .Wrap = wdFindStop
            .Format = True
            .MatchWildcards = True
'Find a str between a tab & the nearest previous para sign, i.e.
'a str between a para sign & a tab, excluding other paras in-between:
            .text = "^13[!^13]@^t"
            If .Execute And rng.End <= rngEnd Then
                .text = "[,:; ]"
                .Replacement.text = "."
                .Execute Replace:=wdReplaceAll
            Else: Exit Do
            End If
'Delete all periods immediately before a tab:
            While rng.Characters.Last.Previous = "."
                rng.Characters.Last.Previous.Delete
            Wend
            rng.Collapse wdCollapseEnd
        End With
    Loop
'Reset rng (see the comment above):
    Set rng = ActiveDocument.Range
    With rng.Find
         .ClearFormatting
        .Replacement.ClearFormatting
        .Forward = True
        .Wrap = wdFindStop
        .Format = True
        .MatchWildcards = True
'Insert periods after lone 1st-level numberings:
        .text = "(^13[0-9]{1,})^t"
        .Replacement.text = "\1.^t"
        .Execute Replace:=wdReplaceAll