You’re not a couple that gets focus until the Cone has seen both people involved together and judged the ship. (Except his own, which he’s admitted he can’t accurately judge. I’m sure Yumi and Shuukichi will get judgement eventually.)
bets on: that handprint was the final omen that made Ford hide the journal, because Bill made the handprint. Ford thought he could use the invisible ink to hide his writing from Bill, but Bill took over his body in his sleep-deprived state and made the handprint—not just to show Ford that the invisible ink didn’t trick him, but to show Ford that, without a doubt, there was no escaping Bill’s possession.