so if the dad cares nothing about the daughter, they treating her like that matter little in a way that they aren't dumb to the point of causing their own demise (like some novels have, people can't be that dumb to ignore their own well being, at least they know how to be selfish, even if being selfish includes feeding someone you don't like).
but he needs to not care at all, to the point even if she is crippled or he needs to attend to her funeral when 'poor thing fell down the stair'.
it is an okay background tho, because the one treating her bad isn't her own family. greed people like that isn't uncommon. sometimes authors really makes it so tragic, that everything becomes such a mess that i don't really feel anything, because it too out of nowhere and a bit too unlogical even to a simplified fantasy.
but if the guy expects them to at least feed her child well, they are pretty courageous to end up mistreating his daughter like that. that is me expecting being a archmage here isn't like very common and actuallly a rare achievement.