What is the ruling on a brother and sister living in the same house not speaking to each other due to the difficulty of dealing with the sister and her instigation of problems, and is it better for each of them to isolate themselves to avoid problems?

Allah has forbidden turning away from each other and abandonment among Muslims, and this is even more severe when it occurs between blood brothers and sisters. Differences in culture or thinking do not justify it. Each party should be forbearing towards the other, overlook their mistakes, and choose kind words. Allah Almighty says: (And tell My servants to say that which is best. Indeed, Satan incites [discord] among them.) [Al-Isra: 53]. The brother and sister should be advised to abandon estrangement, treat each other with good character, avoid argumentation and contention, and seek refuge with Allah from Satan.