So you don't think there's a way to let girls into the boys dorm?
This is controlled by a hard coded section in the exe file plus some parts in the lua scripts. I will have this all disabled in my mega-mod as I know how to do this...but it requires a lot of editing which is why I haven't bothered posting a tutorial on it yet due to being busy with the mod.
Spawning boys in the girls dorm or girls in the boys dorm ...same with prefects not being able to enter is also controlled by this same code....which is also scattered around the exe and various lua scripts for each area and various parts into the game.
The barriers you see at the start of the game that block you f rom exiting the school grounds..or entering certain areas until a certain mission is completed also are controlled this same way.