The other segment in the booking is showing D0 (the flight pass books into D) and I don't want to risk not being able to rebook the other segment if I cancel the whole itinerary. I know, I should book these as separate single segments but I'm: a) a bit dumb and don't learn from my mistakes; b) always in a hurry when I'm making these bookings; and c) not expecting to have to make changes. Pre-COVID these flights were rarely going D0 so wasn't much of a concern but as we know, it's a completely different story now!