This is tough, try giving the family an ultimatum either they make sure their student behaves or both of them get switched to different classes. You can't constantly babysit them and break up fights because it not only obstructs them from learning but also their peers.

The only thing that I could think of possibly doing is to strategically place the students away from each other in the classroom. Maybe also possibly speaking with other colleagues to see if they have a possible solution for the problem or if they are in other teacher's classes (i.e. specials/electives), seeing if this issue is also arriving in their classrooms. This is a very difficult and touchy situation though! I hope that you find a solution and would love to hear what the solution is!

I would involve the parents and keep them in the loop on what is happening in the classroom and what you had done in your classroom to lessen the tension, such as moving them apart and keeping them apart. Give them clear directions on what is happening in the classroom and who is doing what, such as violating rules or the separation that you did. Go to your administration and state what is happening in the class and what you are doing to lessen the tension, and ask what the next steps would be, as you can’t continue with fighting in your class constantly. Ask administration for seperation and after receiving their approval tell the parents what will happen in the fighting continues in class so that they now the consequences

I would have a talk with both of these students outside of the classroom setting and try to come to some sort of solution on how they can be in the same classroom without fighting. I would remind them that their disruptions are affecting the rest of the class and if they can't figure out how to co-exist in the same room that I will get the principal involved to have one of them moved to a different school.

This is a very difficult situation but I do think it could be handled. These students need to understand that adult conversations, fights, or discussions are meant for adults to handle. It would be beneficial to sit them both down and ask them if the other has ever done anything to them. Chances are the answer will be "No" and that they are just following what the adults are doing. Tell them that just because their families have issues it doesn't mean that they do.