It's a schoolyard dilemma many parents will recognise - do you step in and try to keep trouble makers away from your child in the classroom, or stand back and let the teachers take care of things?
But imagine if the child you are trying to keep away from your son or daughter is your own sister's son.
"I don't want my 'awful' nephew in the same class as my daughter," one mum facing that dilemma posted on reddit.
"My issue with this is [my sister's] eight-year-old George. He is in the same academic year as my daughter."
According to the mum, her sister doesn't believe in discipline and, as a result, all her boys are "awful".
"George is by far the worst though. If my sister tells him not to do something he tells her to f-off, or hits her, and she laughs and lets him continue to do as he pleases."
The mum adds that George also thinks her daughter is "his".
"My daughter is not allowed to interact with anybody other than George," she writes. "If she plays with anyone else he screams, cries, hits my sister, swears at everyone, that type of behaviour. Obviously I don't stand for it, and I tell George that my daughter can play with whoever she wants to. My girl is so sweet though that if George cries she gets upset thinking that it's her fault so she does what he wants."
And now the woman's sister wants their kids to go to the same school.
"If my sister is successful in getting her children transferred to our school, George is in the same academic year as my daughter. There are two classrooms per year group so there's a 50 per cent chance he will end up in her class, but I feel she may contact the school to request they are together."
The mum notes that if this happens, the rest of her daughter's time at primary school will be "ruined".
"George will not allow her to play with her own friends, he will disrupt the class and disrupt my daughter."
But while the school itself doesn't decide on transfers, the mum wonders if she would be in the wrong for speaking to the head privately to ask that they be separated if it's approved.
"My sister is NOT one of those people you can talk to about things," she notes. "She takes everything seriously and loves to cause drama, so I'd rather not have to discuss this with her, and just go straight to the teacher now before school ends, rather than go back to school come September and find out the transfer was successful and George has been placed in my daughters class."
The consensus was clear: stand up for your girl.
"It's time to start making waves," one commenter wrote. "Stand up for your daughter and teach her not to accept this controlling behaviour now. Don't stop advocating for her. She's listening and watching!"
"Please do this for your daughter's sake," said another. "Don't ruin his reputation before he even gets there, just explain that due to the family dynamics you'd like them separated."
"Get in there NOW! Your daughter could start to believe this is normal behaviour in friendships, maybe even all kind of relationships, leading to her thinking toxicity is normal in relationships; and accepting it in later life."