Originally Posted by
Scandinavian traveler
Lounge is not dependent on the flights being on a single ticket. Separate tickets are fine, but baggage allowance, security etc. will not work "spill over" on separate tickets.
Not sure if benefits as fast track works on one ticket either, but lounge definitely works regardless. They may reject you at first at the entrance, but the OW rules are quite clear on this so just point to those.
Some FTers recommend taking a printed copy of the rules to be on the safe side for occasions like this..