How do you think Bruno feels about his sister, Gretel's, involvement with the Hitler Youth?

Bruno and Gretel have limited interactions; as brother and sister, they are not very close. She is the more informed older sister and often comes off as a bossy know-it-all. As such, Bruno's judgment in terms of her involvement in the Hitler Youth, and anything she does in general, is likely clouded. In comparison, Bruno reveres his father, a commandant in Hitler's army. He brags to Shmuel that his father is a good soldier because he was promoted to a high rank and wears an impressive uniform. Bruno, being a nine-year-old, knows very little about the Nazi party and the Hitler Youth. He is more fixated on the fact that his father is a good soldier than he is on the fact that his father is contributing to the Nazi cause (an undeniably horrific cause, but in their perspective, a cause nonetheless). Based on the little information provided in the text, in terms of Bruno's references to his sister and his internal reflections, I would argue that he is indifferent to the fact that she is part of the Hitler Youth.