I think it would be a good idea that - just like in books - the Bathroom at the 3rd floor be blocked by a password.
I mean for example, you want to go inside, you click on the link and it asks you for the password. If you don't have it, you can't go inside.
The Prefects' Chef would be the one which choose and change it sometimes (maybe once a year ?) and give it to the Prefects and the Quidditch Captains (once again, just like in the books).
Obsviously it doesn't become a forbbiden zone, because if they want, "normal" Students could totally obtain the password from their friends (or from the best marketers, who knows ?).
Thanks for reading me ! And sorry for my bad english :)
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