It can only be upheld if you can prove that he: abuses her, is intoxicated around her, neglects her such as doesnt feed her and his house is not suitable for children like he had rats etc, if he endangers her etc

If he simply isn't interested in her education and isn't attending meetings it's not good enough to deny him access to her. There are plenty of custodialparents who are these ways and no one takes their kids away. I teach high school and about 2/3 of parents don't attend anything and can't care less how their kids do (tough neighborhood). It's not uncommon

You can certainly talk to your attorney. See what they suggest