Aside from that, my understanding is that a premium longhaul segment with any oneworld carrier qualifies the whole itinerary for lounge access appropriate to the highest cabin on the booking (both at the connecting airport and the domestic/shorthaul airport, and outbound/inbound) providing there is a genuine connection (ie. same day or next available connecting flight to that destination) and regardless of separate PNRs.
In order to constitute a 'genuine' connection does the next flight have to be the same day?
We are travelling long haul First on one PNR North America to LHR, then a separate PNR economy on to Rome. On the outward journey we have several days in London, on the return we have an overnight in London. I realize I would need to have BA move the flights all on to one PNR in order to take advantage of lounge access on the shorthaul - which isn't worth doing if we will not have access due to stopovers.
Sadly we do not have status.
Edited to add - I have no idea why the sad face at the top .... but cannot seem to remove him.