Originally Posted by
ernestnywang
JFK was the only exception, but I don't know if CX will make it a general case in the future.
If you have a look at SYD, the same applies there. At both the F and J Qantas lounges, only 1 guest is permitted, even though the Qantas lounges are the designated lounges for non-Silver members.
Now that I've had a look at some more examples, it appears that where the outstation lounge is operated by another oneworld airline (eg QF or AA), it is Diamond + 1 guest. If the lounge is a CX lounge or a Plaza Premium-type lounge (eg Aspire etc), then it is Diamond + 2 guests.