OT: ORD T5 is a nightmare anyway loungewise. The only decent one there is the AF/KL lounge facing tarmac. BA lounge is small and it is easy to understand why they do not want other OneWorlders to raid their larders. The same goes on with most ohter US and Canadian BA lounges (at least those I know of).
At ORD AY should simply move its departure to T3, also used by AB. There are two Admirals Clubs and even one - though quite small - Flagship Lounge for Plats and OWEs. After all, there is only one AY departure a day.