How is Dark Messiah connected to Heroes of Might and Magic?

The Orcs will also be on Ashan's side, not Shio's. Demons will be in the minority. The Necropolis will most likely side with good, because seven factions are against the demons. And necromancers choose the side of the strongest. Besides, they worship Ashan, and Ashan is against demons. There is no passage to Shio anywhere because it can open in any place. It's like a random hole through which demons penetrate while it hasn't closed.