Not sure if the guests are linked to the main pax in the lounge system as they enter. But the lounge agents asks all pax (including guests) to scan their BP on entering the lounge. This could be to keep a count of how many people are in the lounge, check if the pax & guest are flying on the same day (or some other version of rules). I'd assume, given that the guests also scanning their BP followed by the main pax, there could be a connection/link that exits between the main pax and guest ... again, I could be wrong ... just an assumption here ...