I wanted to share my Qantas First Lounge experience to determine if I fully understand access requirements.

In May I booked business class on the three class trans on A321Ts. Was connecting JFK to YUL. Upgraded with miles to F. I don't know the original fare class booked. Got right in to Qantas first no questions asked

Earlier this month flew the A321T LAX to JFK ending in JFK. Same scenario as above except booked business with AMEX MPs to get 50% back due to bus plat card and upgraded to F on points again. Attendant at Qantas First lounge said we weren't eligible. I argued that we were and he finally let us in never admitting he was wrong. I thought something might be different due to not having the YUL connection but wasn't sure. The attendant clearly didn't have a lot of knowledge as he claimed there are no domestic 3 class flight with F.

Was I correct in assuming I had access both times? I assume it doesn't matter I paid business then upgraded, in advance to first, correct?

The link to oneworld in the Wiki does not clarify access with this scenario, is there something recent and official that I could show an attendant that clearly states eligibility for these transcons? Doing the LAX to YUL. Through JFK again soon. At least I'll have Flagship Dining and lounge to fall back on if not....