What sort of theories do you invent to fill in the blanks? One theory I've entertained is that our-universe-Kochanski never died in the accident. Holly says Frankenstein and her kittens were safely sealed in the hold during the accident. Who put them in the hold? Our-universe-Kochanski knew about Frankenstein, so maybe she put her/them in the hold, and got put into stasis herself. We're specifically told there are two stasis booths. Parallel-Universe-Kochanski got put in stasis for hiding Frankenstein, right? We've never seen the other stasis booth. Okay, so my theory requires that Holly lied/forgot when he told Lister she was dead, and that no one's ever noticed her in the other stasis booth in all these years. But I still imagine an episode where we get a "three million years ago" and see Kochanski comically smuggling a load of cats down the corridor while a "warning: unquarantined cat aboard" sign flashes, and someone notices her. She puts them in the hold, then gets called before Hollister like Lister did, and similarly refuses to reveal their whereabouts, thus winding up in the other stasis booth. Maybe some sort of secret stasis booth. There was a whole secret floor, after all.