Originally Posted by
Justin Choi
I have bought the CX tickets as an open jaw itinerary
HKG-FRA
LHR-HKG
but would like to add a BA flight from TXL to LHR to connect with the ex-LHR flight to HKG.
You can only do it if you buy from a TA, and by now it's probably too late (since the CX ticket is already bought).