There are a few options. One, someone could kill tonight to make sure the numbers are what the voice wants.

Two, we try to make sure no one kills and see how much the voice is lying or telling the truth.

Three... there should be more options, but it requires finding more answers than what we have.

[ Honestly, Shinobu isn't happy with any of this right now. They all saw what happened to Kairi, so it's not like the voice hasn't proved anything. She just doesn't want to be compliant with something she doesn't agree with. ]