I'm Lucy, and I'd be happy to answer your questions today. I'm sorry to hear about your situation.
If your daughter's mother is refusing to see that her homework gets done, destroying it so it doesn't get handed in, and otherwise interfering with your daughter's grades (and, honestly, her future, if this continues), that could actually be grounds for you to request a change in custody. Your daughter deserves to be with the parent who is going to give her a chance to succeed (or at least, not hinder her chances). Not only could not doing her homework lead to being held back (which is going to cause bigger problems), but seeing her mother throw tantrums and behave like a child isn't going to help with her development, either. So, you could actually file a Motion for Modification, asking that you have custody on school days to ensure that your daughter is getting something from her schooling. Your daughter can actually tell the judge what types of things she's seen, but if you could get documentation from a teacher about what's happening and your daughter's performance in school, that would help significantly.
Another option is to file a Motion asking the judge to order the mother to give you your daughter's homework, turn in the homework when she's with her, and otherwise assist in her education as needed. That way, if she keeps going the way she is, she's in contempt of court. The only issue is, it's tough to monitor, and you could wind up back in court several times. But it's an alternative for the judge if he doesn't want to change custody completely, and you're allowed to file one motion that makes different suggestions for how to address this problem.
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