Just following on from this today I booked a Gold Prority Reward booking and wanted to hide it from the other passenger (as it’s a surprise) so asked that they didn’t include their BAEC number. Received the confirmation and no frequent flyer number was included. A few hours later I can see that the booking has now snuck into their account somehow and I can’t seem to remove it. I added their number on Finnair and removed it again but it’s still there.

Any advice?