We understand your distress and desire for reconciliation, but let's remember that God works in each person's life in His own way and timing. It's important to pray for A, C, and D with a heart of compassion, rather than seeking to correct them through divine intervention. The Bible tells us, "Don't repay evil for evil. Don't take revenge. Instead, let the Lord's wrath take care of it. As it is written, 'Vengeance belongs to me; I will repay, says the Lord.'" (Romans 12:19 WEB)
Firstly, let's address the issue of your forgiveness. God is faithful and just to forgive us our sins and to cleanse us from all unrighteousness (1 John 1:9 WEB). So, you can trust that as you confess your sins, God forgives you. Also pray for them asking God to give you His love for them and His strength to forgive. Jesus is the One who has saved us and given us access to the Father. It is in His name we pray. There is no other name under heaven given among men by which we must be saved (Acts 4:12).
Regarding your brother-in-law, instead of asking that he leave you alone forever, consider praying for a reconciled relationship, One that's built on mutual respect and understanding if he is a Christian.. Jesus said, "But I tell you, love your enemies, bless those who curse you, do good to those who hate you, and pray for those who mistreat you and persecute you," (Matthew 5:44). Jesus also said, "For if you forgive men their trespasses, your heavenly Father will also forgive you. But if you don't forgive men their trespasses, neither will your Father forgive your trespasses." (Matthew 6:14). Also, you are told to love your enemies. It may be that he is your enemy, but you are to do good to him. Pray for God to help you.
As for your children, trust that God loves them even more than you do. Pray for His will and His best for them. "Train up a child in the way he should go, and when he is old he will not depart from it" (Proverbs 22:6 WEB). Ask God to guide them and protect them. He is the perfect parent.
Now, let's pray:
Heavenly Father, we come before You in Jesus' name, lifting up Swantalelf and their loved ones. We ask that You work in the lives of A, C, and D, softening their hearts and revealing to them any areas where they need to repent and change and only if it is Your will. We pray for Swantalelf, asking that You forgive them and give them wisdom and understanding. Help them to forgive and let go of resentment, and fill their heart with Your love and peace for their brother-in-law and everyone. We ask that You guide Swantalelf and their children, providing for them and working all things together for their good and Your glory. Help Swantalelf to look to You for forgiveness for themself and others. Give Swantalelf Your love for them. And may You bless Swantalelf and their children. We ask this all in Jesus' name. Amen.
Lastly, remember that God is working everything out for your good (Romans 8:28 WEB). Trust in Him, and He will direct your paths (Proverbs 3:5-6 WEB).