Dear members of TQC, can I extract some advice, wisdom, or knowledge?

My youngest sibling recently switched schools middle of the semester. It shouldn't have been an exceptionally big deal because her school was supposed to be ahead in the subjects anyway, however, when they switched her they took her from pre-algebra and put her in honors algebra. At first she was like, "oh it's the same thing, I'm not having any trouble." And awkwardly my father let it go, trying to trust her sense of judgement. Last night however she's crying to me that she doesn't understand any of her home work and she can never remember anything and her teacher didn't teach any of the stuff on her home work. Frequently she comes home and I have to teach her everything on her homework. It wouldn't be so bad if she didn't spend a week at her mom's where I don't see her. Anyway, this homework she was supposed to be doing was the pretest review, and she couldn't handle any question without prompting her first. I recommended that she go back into a pre-algebra course after we finished the homework, which took two and a half hours. She started denying having any problem at all. Saying things like, "oh I just wasn't focused." "I just needed to be reminded." "It's not that hard." Then down to "I'm fine. I'm fine. I'm fine. "

ETA: I forgot to mention this. I have talked to my dad about it, and he's tried to talk to her about it. Tried to reassure her that it's not a big deal or make her stupid, he just doesn't want to see her struggle the way he did in math because people forced him to move up even though he wasn't ready. He was met with the same "I'm fine. I'm fine. I'm fine."

I want to help her. I really don't recommend this class for her. I certainly can't motivate her to be tutored after hours of homework to catch up. So. What do I do?