terenz,

i was booked on a CX flight from HKG-MNL-HKG on the same day in the same record. As a matter of fact I flew back on the same airplane with the same crew. The agent in MNL took my number and was able to successfully change the number without affecting credit for my first flight.

If you are going to give any numbers I would call cathay and tell them what u want. then verify this was done at check in. If u are on a same day return and simply add a number to the record on the return u risk a bactch job of some sort picking up the number for your first leg also.

u might be better just sending in both to the airlines.

good luck,
rich