Correct! Seems like I was able to do this. I initially sent DM via Twitter to remove from both segments, taken care of in less than 4 hours. There was no line at KUL so I went to the Business Class counter and asked if they could add back my FF number to just the KUL-HKG segment they said sure no problem. They also removed from the HKG-JFK segment because for some reason it repopulated? The agent showed me the boarding passes to confirm. So seems like it’s all going as planned. Will report back if it doesn’t in case this info is helpful to anyone else.