nobody is saying they do not HAVE a return ticket, they are not starting their journey without a return flight in hand. The question asked is regarding purchasing it separately; so the traveler has two one-way flights as opposed to one 'round-trip'.hand over your ID to the check-in person who then ONLY sees your one way ticket to anywhere.
So when the ID is handed over, and they put it into the computer, they will see that there is another flight scheduled, returning to the US. Even if it's not purchased thru a consolidator, and was bought as a totally separate individual purchase, it will still show up .... just not on the same airline purchased specifically as a "round trip".
Buying tickets this way is not an issue - especially since there are three of them, and the computer will show all three traveling together, on the same flights, both outbound and inbound ---
--- that's what the OP wanted to know.
