If a rolelist contains two or more Vampire slots, only one should spawn a Vampire whereas the rest act as
Common (Town) slots that start as part of the Vampire faction.
Why?
Modded Vampire is a pretty cool concept for conversion, however because of the nature of it you can't have more than one of it. This also means that if you want to balance a rolelist around Vampire, you have to have a third party exist.
This solves the issue by giving evils more numbers at the start without adding an extra side, and in addition, if the Vampire is found on N1 after having missed a conversion, the entire team isn't screwed. (This also means you can afford to not convert N1)