In my mind, there’s really only two main issues. Ochi’s ship matching the ship in Rey’s flashback, and Kylo’s dialogue. Visually change the look of the ship in the flashback, and untangling the rest of the parents/Ochi connection is simple - Rey doesn’t mention recognizing the ship, Ochi has nothing to do with her parents, we don’t see him kill her parents in the flashback. The dagger doesn’t trigger her flashback in the existing film anyway, it’s Kylo saying something like “remember them” while they’re fighting.

In effect you’d just remove Palpatine’s involvement in her parents death at all. So Kylo brings up her parents to remind her that she actually killed them (implied that Palpatine told him), and uses it as fuel to get her to join him on the dark side. Palpatine is only referenced as the thing they need to join together to beat. Some of the dialogue to fit this is already there, but there’ll also need to be some extra Kylo dialogue to do some heavy lifting. The question is if that dialogue can actually be cobbled together with what exists out there.