Should the starting hero for Necropolis be chosen randomly?

Question: what should be done in this case with Isro and Vidomina? Until the necromancy amplifier is built, let them roam around and not develop their spellcasting skills to the expert level. After the amplifier is built, require them and other heroes with advanced spellcasting skills to be dismissed within 2 turns from the day of construction.
Necromancy amplifier + basic spellcasting = 20% more skeletons raised. This seems quite acceptable to me. It will be interesting.