The code adds a row to the table, splits that off, merges its cells, then replicates the row at the top of the table, before deleting it and filling the new row at the top of the table with the 'Attachment' text.
It would have been helpful if you had said you only wanted to process two specific tables. You could simply add an If test to the 'With Tbl' block to check what the preceding paragraph contains. For example:
Code:
With Tbl
If .Range.Characters.First.Previous.Paragraphs.Last.Range.Text Like "Attachment [3-4]" & vbCr Then
...
End If
End With