Originally Posted by xliioper

You can split PNRs where you have two or more passengers on same reservation (each passenger has their own ticket) so that they are on their own reservation or grouped on separate reservations. However, you can't split a roundtrip booking (which will be on one ticket even though there are multiple fares involved). As noted, you'll need to cancel original roundtrip ticket and then book two separate one way tickets. This is not the same thing as splitting PNRs.