Start playing the edit in your DVD or BR player. Once the certain scenes begin, eject the disc and put in the original. When the sequence is over, put the edit back in.
Pretend they’re LaserDiscs. Everything’s better on a LaserDisc!
But really, dedicate just a few hours to looking into how to edit together video clips. You wouldn’t need anything fancy at all, just splitting a video into clips and then rejoining them.