It makes sense thematically, and werewolf-type games need the hidden people to have various powers.

  Though I note that the title should be “Murderes and Detectives don’t know Cartlesham Manor”.

CoV   per alethiophile.

I’m concerned this would make it too easy to completely rule out non-Servant suspects - whenever there’s an attack, then every non-Servant on every other floor must be innocent of it. (Although that doesn’t mean they aren’t a murderer, just that they didn’t commit that particular murder. But if there are two attacks in one period of darkness, then two or three entire floors can be confirmed as murderer-free.) It should be harder work to prove someone innocent, than simple taking turns to hide in the attic.

S/K i see Kevans point.