My antidote to people coming up with "local rules" is to print out the alliance conditions and stick to my guns!
(I was once in a situation flying (then) Alitalia intercontinental in Y (or maybe W, but anyway not J), transiting to an intra-European flight in J (because for some reason the overall trip was cheapest that way). At the time the rules seemed to allow access to the lounge at the departing airport, though I seem to remember they were arguably ambiguous (it was something like "you may access the lounge if you are connecting to/from a business-class flight"). I (politely) argued the toss with the lounge dragons (I think maybe it was a Delta lounge or something), spoke twice to Alitalia on the phone, said I would follow up with a complaint ... and in the end they let me in!
The current rules,
https://www.staralliance.com/en/lounge-access-policy , are arguably still ambiguous:
As an International Business Class Customer you have access to any Star Alliance member carrier’s owned Business Class lounge at the airport where your flight departs, if the following conditions are met:
- You present a boarding pass in International Business Class on a Star Alliance member airline operated flight
- Your flight departs on the same day of your visit or latest by 05:00 AM the next morning
Does a boarding pass for a flight you will connect to (as opposed to the flight you will be taking next) count?
)
I don't think there's any requirement to know your guest (well, to have known your guest for more than 5 seconds). I am not sure of the origins of the guest rule, but I had always thought of it as being in part a marketing tool: "hey look, if you were flying business with <airline> or had elite status in <airline programme>, you too could be enjoying this life of pampered luxury!", so I am not sure it's against the spirit of guesting someone.