Jesus said in Matthew 10:34 that He did not come to bring peace to this world.
There will always be divisions as long as we live on this earth. We will have those that cause strife and confusion where ever they are. Satan is the author of confusion and the prince of this world. Just have comfort in knowing that, there will come a time when we are going to a place where there is peace, love and no confusion. But, I pray that those that have been dealing with this unruly family, will find peace in their hearts. I have found that trouble don't last always. There are so many people on this earth with that type of behavior as the people you have described. Prayer can change things though. People like that have hardened their hearts against justice and righteousness. We must continue to pray for them that their hearts will be replaced with a Christian love for their fellow man/woman. The bible says in Romans 8:28. "And we know that all things work together for good to those that love the God to those who are the called according to His purpose.
Just as the Israelites had to deal with Pharoah, and they were delivered. Those that trust in God will be delivered from their oppressors as well.
Don't let these people get the best of you all. Just continue to lift your neighbors up to God. Be the example each day that God wants you to be.
Be blessed in the Lord.
Father God, bring peace to the hearts of these people. Show them that Your love will always abound. Let them not fret over evil doers. I ask in Jesus name. Amen!