We already brainstormed around on Discord, but let me hop in here for posterity!

We could send the two bastard boys at the tower... they might even be able to skip the dark room / bubble room, because at the sight of the weird purple cloud on the staircase Hijikata may just make a u-turn and fly them up to that window instead (or we can skip that part and dump them in the butterfly room together)! OR we can send them into the maze!!

And of course we'll double-dip for later shenanigans between kid Levi and adult Hijikata... sorry, Levi, the other brat became a cop!