Mafia 90. The Tale of Oldforest.

Then a situation may arise where several people get the same number of votes, and either everyone has to be executed, or, again, the poor NNV has to take the blame.

Oh, there are many options here:
1. A special role, "Judge," who decides who gets hanged.
2. A lottery among the candidates for the role of the lucky one.
3. NNV. That is, the only way to get NNV in some games is a situation with several players who get the same number of votes.
But in general, I agree with Yashur. For Hv-mafia, the absence of NNV is an unnecessary heresy. It reduces the possibility of maneuvering.