Changing Unit Races

[Damask]

Just wanted to ask if anyone might have an idea how to do this? I'd like to make a mod where Undead and Demons can be healed and resurrected (because they are highly inferior without this imho) and I thought that simply changing them to a different race might do it. I can't seem to locate the right file to do it though and was wondering if anyone had any advice?

Thanks!