Macro to open closed file append new rows, and update existing rows

I can open the newest version of the closed file and import it whole but I have tried but can not get how to append new rows, and update existing rows

Thank you

I need

Sub UpdateSheet()
Dim MyFilePath As String

Application.ScreenUpdating = False
 MyFilePath = ThisWorkbook.path & "\myWorkbook\"
 
'Open The most resent file
 Workbooks.Open MyFilePath & NewestFile(MyFilePath, "*.xlsx")

'For each row in data export file (the file just opened), starting at Row 2

'Check master data file (column A) unique ID column

'If ID # exists, update information in columns B through last column

'Else add new ID row and place information in columns A through Last column

'Next row

End Sub