NHF – new heroes for Heroes V 3.1.

What do you mean?
Make it so that the mod doesn't contain any heroes, and they need to be added manually.

The list of all new heroes is stored in map.xdb. It's not possible to split map.xdb.
However, I'm not sure. Dyrman, maybe it's possible to have all heroes in map.xdb? If there are extra links, will it cause glitches? Or will it?