What you can do inside your parse function is to build a dictionary with the customer names as keys.
Now you have to add every VPN session found for this customer to a list of sessions inside the dictionary.
parsed = {}
parsed['customer1'] = []
add data here 
return parsed
now build your session data and append the entry to the empty list
To discover your items it is possible to use the discover() function as you have a dictionary with keys that can be used as items.
The easiest check later is then only count the length of your list to have the amount of active sessions for this customer. But you can also make more like traffic calculation and so on. If the data is stored in the list