Sorry for the delayed response. It was one ticket, but delays leaving the US caused a rebooking so I'll have to check if something may have happened to split the reservation onto two tickets. It was a DL-coded DL flight from the US followed (in J) by an AF-coded AF flight (in Y).

Since I originally wrote I have reviewed the intinerary printed by AF staff @ CDG for the last flight. It shows Y class with 0PC allowance, which is extremely odd.

There was a issue at the gate so had to visit the customer service desk, where they proceeded to demand payment.