The prequels also mention pre-destiny and premonitions of the future, in this way I think not only can you use flashbacks to prequel moments in the epilogue, but ominous flashforwards in the prologue. This could also help solve the “save the reveal” while not omitting key scenes you really want to show, you can decide what surprises to prepare people for early and later resolve hanging questions that show for example Anakin fall to the dark side and become Vader as Kylo is redeemed.