how to differentiate pdf files files in a folder by file name and merge into pdf files based on last modified date using VBA

According to my work,I have a  folder which contains some pdf files.

1.I need to merge files into 2 separate files.(File names ends with ABCRDF & ABCOSD into single merged file and all other pdf files into another merged file.
2.So after merging we will have only 2 pdf files.One which contains file names ends with ABCRDF & ABCOSD.And other merged file with all  files except above 2 files.
3.Merging should be done by last modified time stamp.

I have code which merge all the files present in a folder into a single pdf based last modified time stamp.It wont differentiate files based on file names.It will take all the files present and merge to a single pdf file.I will attach the same here.


Any help regarding this would be greatly appreciated..!!

Sub Main()

    Const DestFile As String = "MergedFile.pdf"
    
    Dim MyPath As String, MyFiles As String
    Dim a As Variant, i As Long, f As String
     
     ' Choose the folder or just replace that part by: MyPath = Range("E3")
    With Application.FileDialog(msoFileDialogFolderPicker)
         '.InitialFileName = "C:\Temp\"
        .AllowMultiSelect = False
        If .Show = False Then Exit Sub
        MyPath = .SelectedItems(1)
        DoEvents
    End With
     
     ' Populate the array a() by PDF file names
    If Right(MyPath, 1) <> "\" Then MyPath = MyPath & "\"
    Set sh = Workbooks.Add.Sheets(1)
    Set Rng = sh.Range("A1") ' or wherever; doesn't matter

    Set fso = CreateObject("Scripting.FileSystemObject")

    f = Dir(MyPath & "*.pdf")
    While Len(f)
        iFil = iFil + 1
        Set fsofile = fso.getfile(MyPath & f)
        With Rng.Cells(iFil, 1)
            .Value = fsofile.Name
            .Offset(0, 1).Value = fsofile.DateLastModified
        End With
        f = Dir()
    Wend
    With sh.Sort
        .SortFields.Add Key:=Rng.Offset(0, 1).Resize(iFil, 1), Order:=xlAscending
        .SetRange Rng.Resize(iFil, 2)
        .Apply
    End With
    If iFil Then a = Application.Transpose(Rng.Resize(iFil, 1))
    Application.DisplayAlerts = False
    sh.Delete
    Application.DisplayAlerts = True
    
     ' Merge PDFs
    If iFil Then
        MyFiles = Join(a, ",")
        Application.StatusBar = "Merging, please wait ..."
        Call MergePDFs(MyPath, MyFiles, DestFile)
        Application.StatusBar = False
    Else
        MsgBox "No PDF files found in" & vbLf & MyPath, vbExclamation, "Canceled"
    End If
     
End Sub
 
Sub MergePDFs(MyPath As String, MyFiles As String, Optional DestFile As String = "MergedFile.pdf")
     
     ' Reference required: VBE - Tools - References - Acrobat
     
    Dim a As Variant, i As Long, n As Long, ni As Long, p As String
    Dim AcroApp As New Acrobat.AcroApp, PartDocs() As Acrobat.CAcroPDDoc
     
    If Right(MyPath, 1) = "\" Then p = MyPath Else p = MyPath & "\"
    a = Split(MyFiles, ",")
    ReDim PartDocs(0 To UBound(a))
     
    On Error GoTo exit_
    If Len(Dir(p & DestFile)) Then Kill p & DestFile
    For i = 0 To UBound(a)
         ' Check PDF file presence
        If Dir(p & Trim(a(i))) = "" Then
            MsgBox "File not found" & vbLf & p & a(i), vbExclamation, "Canceled"
            Exit For
        End If
         ' Open PDF document
        Set PartDocs(i) = CreateObject("AcroExch.PDDoc")
        PartDocs(i).Open p & Trim(a(i))
        If i Then
             ' Merge PDF to PartDocs(0) document
            ni = PartDocs(i).GetNumPages()
            If Not PartDocs(0).InsertPages(n - 1, PartDocs(i), 0, ni, True) Then
                MsgBox "Cannot insert pages of" & vbLf & p & a(i), vbExclamation, "Canceled"
            End If
             ' Calc the number of pages in the merged document
            n = n + ni
             ' Release the memory
            PartDocs(i).Close
            Set PartDocs(i) = Nothing
        Else
             ' Calc the number of pages in PartDocs(0) document
            n = PartDocs(0).GetNumPages()
        End If
    Next
     
    If i > UBound(a) Then
         ' Save the merged document to DestFile
        If Not PartDocs(0).Save(PDSaveFull, p & DestFile) Then
            MsgBox "Cannot save the resulting document" & vbLf & p & DestFile, vbExclamation, "Canceled"
        End If
    End If
     
exit_:
     
     ' Inform about error/success
    If Err Then
        MsgBox Err.Description, vbCritical, "Error #" & Err.Number
    ElseIf i > UBound(a) Then
        MsgBox "The resulting file is created:" & vbLf & p & DestFile, vbInformation, "Done"
    End If
     
     ' Release the memory
    If Not PartDocs(0) Is Nothing Then PartDocs(0).Close
    Set PartDocs(0) = Nothing
     
     ' Quit Acrobat application
    AcroApp.Exit
    Set AcroApp = Nothing
     
End Sub