My instinct would be that he's probably going to discount anything he hears from you--he's already set up rationalizations to tune you out.
However, I think this is a place where it would be really useful for your D to express herself to her father. This is a skill she needs for all her future relationships, and thinking like "I'm afraid to tell X something because..." becomes a destructive ingrained habit.
However, if a face-to-face discussion would be too difficult for her, perhaps it would be easier to get it all down in a letter? This would diffuse tensions, let her express herself fully, and give him a chance to re-read it in a calmer state of mind.
My other suggestion would be, since she has a C, could she invite H to come to an appointment so she could talk these issues through with the support of her therapist? The C could gently guide H in how to resolve your D's hurt.
