VBA to merge multiple workbooks with demarcation

[akin]

Pls, I need help on how to merge multiple excel workbooks into single worksheet but with demarcation. I mean I want to know where one workbook data starts and ends, preferably filling the entire first column with workbook name.
What this mean is that as each workbook is copying to the new worksheet, it will pick its workbook name and use it to fill entire first column in the new worksheet and do that to all workbooks.
I had tried the code below before but I was not able to know where one workbook data starts and ends. And I need that knowledge to be able to proceed with further analysis.

Sub Button2_Click()

Dim path As String, ThisWB As String, lngFilecounter As Long
Dim wbDest As Workbook, shtDest As Worksheet, ws As Worksheet
Dim Filename As String, Wkb As Workbook
Dim CopyRng As Range, Dest As Range
Dim RowofCopySheet As Integer

RowofCopySheet = 2 ' Row to start on in the sheets you are copying from

ThisWB = ActiveWorkbook.Name

path = GetDirectory("Select a folder containing Excel files you want to merge")

Application.EnableEvents = False
Application.ScreenUpdating = False

Set shtDest = ActiveWorkbook.Sheets(1)
Filename = Dir(path & "\*.xls", vbNormal)
If Len(Filename) = 0 Then Exit Sub
Do Until Filename = vbNullString
If Not Filename = ThisWB Then
Set Wkb = Workbooks.Open(Filename:=path & "" & Filename)
Set CopyRng = Wkb.Sheets(1).Range(Cells(RowofCopySheet, 1), Cells(ActiveSheet.UsedRange.Rows.Count, ActiveSheet.UsedRange.Columns.Count))
Set Dest = shtDest.Range("A" & shtDest.UsedRange.SpecialCells(xlCellTypeLastCell).Row + 1)
CopyRng.Copy Dest
Wkb.Close False
End If

Filename = Dir()
Loop

Range("A1").Select

Application.EnableEvents = True
Application.ScreenUpdating = True

MsgBox "Done!"
End Sub

Thanks alot