I ran into a limitation today for the first time with guesting at a Qantas Club. The Admirals Club membership provides access for two guests at Admirals Clubs. I've also been able to guest in two people at Alaska Lounges as well. Today, I was informed that Qantas Clubs limit to one guest, even for those wanting to access a Qantas Club using an Admirals Club membership. I'm not entirely convinced of this answer because the staff at the counter for the Qantas Club at Terminal 3 at SYD kept saying, "As an Emerald member, you can access the Business Lounge with one guest." I tried to interject multiple times to indicate that, "No, I am not relying on my oneworld status today but rather trying to use my Admirals Club membership for access to a Qantas Club." The agent didn't even want to look at my Admirals Club membership information.

The only policy that I can find referenced for the Admirals Club membership is here. In particular there is this line:

I'm ignorant on the T&Cs of a Qantas Club membership, but a cursory search indicates that a membership only provides access for one guest. There was no information I could find specifically referencing guesting at Qantas Clubs for Admirals Club members, however.