Responses
Basically, since she has the light ability, the temple and the imperial family will try to take her for themselves, each fraction wants to have the light ability. So in order to avoid anyone from trying to snatch her away from her family, they made her the head. By being the head of the family, her duty with her family makes it harder for anyone to take her.

I think I read too long ago and don’t remember, and don’t want to reread to look at that abusive grandfather of hers== on a side note why can’t they protect a child from him and keep being all gentlemanly, just fry that old maaan