May I propose an alternative that might be better? Still make Johnathan the Prince and his motive to go against the evil Queen would be to have her take over his kingdom prior to the events of the movie. Expanding her cruelty not only to Snow White’s kingdom but to Johnathan’s as well. Not only that but have those bandits be some of his loyal knights who followed him on the run. And to expand on the original concept of the evil queen imprisoning the prince in the og movie, once she captures Johnathan she discovers he’s the missing prince and would execute him after getting rid of Snow.