Isolate the last 3 used area of the column

Hello, few years back. I do have problem finding last empty cell on a column and inserting, copy paste the last non empty column. Now, I do have same problem again but this time I have to copy the last 3 non empty columns and paste it on 3 inserted column. Here is the piece of successful code with my previous problem. Hope you can modify it. Thanks!

Sub AddCol()
    Dim rng As Range, c As Range
    Set rng = Intersect(ActiveSheet.UsedRange, Rows(2)) ' Isolate row 2
    If rng Is Nothing Then Exit Sub ' Assuming there is more than one row
    Set c = rng.Cells(rng.Cells.Count) ' Isolate the last cell in row 2
    If IsEmpty(c) Then Set c = c.End(xlToLeft) ' Find the last non-empty cell
    If Not IsEmpty(c) Then
        Set rng = Intersect(c.EntireColumn, ActiveSheet.UsedRange) ' Isolate the used area of the column
        rng.Copy ' Copy to clipboard
        rng.Insert Shift:=xlToRight ' Duplicate
        c.Offset(0, -1).Select ' Select the "marker" in the duplicate column
        Application.CutCopyMode = False ' Switch off the CutCopy marquee
    End If
End Sub