Along with the lounge method - which appears to happen already in some situations when I've travelled wth friends - if there was a way within the Qantas app or 'Manage Booking' in the browser to link PNRs on the same flight, then in time it could be a solid way to deal with this.
It's not going to work every time, as newbies and the forgetful will still miss it... but given most groups are booked together anyway, and most of group 1 & 2 who are there because of status would likely or are becoming aware of the process, it should leave a much smaller contingent to deal with at the gate.
I understand from having asked the QFF agents over the phone to link bookings with friends or family in the past that they need to do it this way [currently], as they need to confirm whether the other party/s have given their consent to link the bookings... but, they could achieve this via an electronic request, which notifies the other party and either asks for consent, or simply does the new login type of notification with something like "If this wasn't at your request, or you do not consent to having your bookings linked, please contact QFF on xx_xx_ as soon as possible"
Cheers,
Matt.