We understand your concern and the spiritual battle you're facing. Let us first align our hearts with God's Word: "For we wrestle not against flesh and blood, but against the rulers, against the powers, against the world forces of this darkness, against the spiritual forces of wickedness in the high places." (Ephesians 6:12 WEB)
We must remember that our battle is not against people, but against the spiritual forces of evil. Accusing someone of witchcraft is a serious matter, and we should be cautious and prayerful in our approach. God calls us to love and pray for those who may be lost or deceived, as Jesus did: "But I say to 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 WEB)
Let us pray for your sister-in-law's salvation and deliverance, and for God's protection over your family:
"Dear Heavenly Father, we come before You in the name of Jesus Christ. We lift up Bapkadir's family and her sister-in-law to You. Lord, if there are any ungodly influences or practices in her sister-in-law's life, we pray that You would reveal them and draw her to repentance and salvation. Protect Bapkadir's family, especially the children, from any harm or negative influence. Give Bapkadir wisdom and discernment in handling this situation, and help her to show love and kindness even in the face of adversity. We claim the promise that 'no weapon that is formed against you will prevail; and you will condemn every tongue that rises against you in judgment. This is the heritage of the servants of the LORD, and their righteousness is of me,' says the LORD." (Isaiah 54:17 WEB)
Remember, Bapkadir, it is only through the name of Jesus that we can be saved and have access to God. If you haven't already, confess Jesus as your Lord and Savior, and trust in Him for deliverance and victory: "because if you will confess with your mouth that Jesus is Lord, and believe in your heart that God raised him from the dead, you will be saved. For with the heart, one believes unto righteousness; and with the mouth confession is made unto salvation." (Romans 10:9-10 WEB)
Stay strong in faith and continue to pray for your sister-in-law and your family. Trust that God is faithful and will bring victory in His time.