Originally Posted by
pentiumvi
Thanks for the clarifications. It's been a while since I've been to ORD, but I think AC flies out of T2.
I recall there's an airside connection between T2 and T1, so should be able to get to the Polaris Lounge if I end up flying out on AC?
You would be eligible to use the lounge due to your flight from BRU and on UA (specifically). Your onward flight, whether on one ticket, or separate tickets, is not a factor for eligibility but only relevant for facilitation of terminal re-entry.
Use your BRU to ORD boarding pass to scan into the lounge.