Check everyone's luggage under the two people travelling together on CX 883. So that the other person travelling on CX 881 has no luggage to deal with should his flight clear by the time everyone gets to LAX. It will be much easier for him / her to change BPs than for CX to hunt down the bags. The alternate is to check the bags only to LAX, and then take the bags to TBIT yourself.. but given the loooooong security line-ups at TBIT involving international flights, that may be troublesome.