I would try to communicate what you have been noticing in the classroom to both sets of parents. This way they can both address the behavior problem head on together. Also making sure a good and steady routine is in place in the classroom, the child already has lack of stability at home, that being at school should be a place of comfort and normalcy

I believe that it would be good to talk to both parents, probably at separate times, to discuss what is going on with the student. You can observe the different habits the student has when they are staying at each parents house. This would be useful so that you can make each conference unique to how the student is behaving. Come up with solutions with both parents to best accommodate for the child in the class.

Unfortunately, teachers have no control over the home-life of the student, but we do have control over their school life. Sometimes it might only be necessary to talk to the student. Get to know them and what they like/don't like. For example, in talking to the student, he/she might mention that they did not do anything fun over the weekend because they were at dad's house and dad is too strict. From this, you know that chastising the student will only shut them down. Especially if the student is younger, a simple strategy like utilizing positive reinforcement could get a better reaction from the student than bringing the parents into the situation. Of course, should the issue continue, one might consider a parent-teacher conference, separately with each parent. However, this might or might not solve the problem. I would definitely start with the student first. Sometimes they just want someone who cares.

Speaking to the parents might be an "eye-opening" opportunity for them. If not, redirecting the behavior through a teacher-student agreed upon plan could support the whole classroom.

Try and make sure that the child trusts you as a teacher and knows that your classroom is a safe space for them. The student may need that structure and may need to be told that they have that structure. I would also call a meeting with both parents and explain to them what is going on. Involve administration so that nothing gets taken out of context.

As the teacher, I would set time aside to communicate with both parents so that they are better informed of the situation that is occurring at school because the parents may not be aware of this or of the affect that its having on the child. I would also take some time to speak to the student about how they are doing, to see if they open up about anything.

You may not be able to control the student's home life and what they are experiencing, and it seems like this child has no set routine to rely on which can be really stressful for a student. Making sure your classroom has a set schedule and rules will allow the child to adjust to what they CAN rely on at school. With the parents, they may or may not care about what you have to say about their child acting out at school but at a minimum, you owe it to the student to reach out and see what the parents can do to work with you to help the child. I would first though start with the student and sitting down to talk to them, just explain that you have noticed they have been acting out of character and that you want to help. Sometimes students just need someone to listen to them and that is all that is takes so I would start there and if things continue then go to the parents and see if that helps.

The teacher needs to do their best to make it a stable classroom. If the student feel more stable in the classroom then the teacher might see less behavior over time.