Originally Posted by skywardhunter

no need to be on same PNR.

technically even on the same PNR there is no explicit entitlement to priority check-in or boarding, though practically i don't think anyone will stop you.

For lounge access it's completely irrelevant, the only thing that matters is being on the same onward flight.

Originally Posted by ukdoctor

AFAIK you can split a PNR but not sure if u can combine PNR's.

You can ask for a note to be made that u are travelling together ..