Sub MergeDocs()
Dim rng As Range
Dim MainDoc As Document
Dim strFile As String
Dim Count As Long
    With Application.FileDialog(msoFileDialogFilePicker)
        .Title = "Pick files"
        .AllowMultiSelect = True
        If .Show <> -1 Then Exit Sub
        Set MainDoc = Documents.Add
        For Count = 1 To .SelectedItems.Count
            strFile = .SelectedItems(Count)
            Set rng = MainDoc.Range
            With rng
                .Collapse wdCollapseEnd
                If Count > 1 Then
                    .InsertBreak wdSectionBreakNextPage
                    .End = MainDoc.Range.End
                    .Collapse wdCollapseEnd
                End If
                .InsertFile strFile
            End With
        Next Count
    End With
    MsgBox ("Files are merged")
lbl_Exit:
    Exit Sub
End Sub