There is only one way to approach the matter, and that is by prayer alone as is written in (Philippians 4:6 NKJV) “Be anxious for nothing, but in everything by prayer and supplication, with thanksgiving, let your requests be made known to God; and the peace of God, which surpasses all understanding, will guard your hearts and minds through Christ Jesus.” So then, let’s put our prayer request to God for that self-willed son or daughter, and let God transform them inwardly, by the renewing of their mind, that they may prove what is that good and perfect will of God (Romans 12:2), as follows:
”Lord Jesus I offer to you my thanksgiving and praises, for the (son/daughter) you have blessed my life with. I come before you now with my thanks for bringing their self-willed character to a close, and bringing them into the true nature and conduct of respect and love of wisdom to hear and obey the voice of God’s authority through their listening to father and mother for their good.
I beseech you Lord Jesus to bring them to know the truth, and the truth will set them free. For I know, believe, trust and receive all your promises of faithfulness in trusting your will for their good outcomes in life as you have declared in (Jeremiah 29:11 NKJV) “For I know the thoughts that I think towards you, says the Lord, thoughts of peace and not of evil, to give you a future and a hope.”
So be it Lord Jesus to do it, for God is and God will provide for them as is written in your Word of truth the Bible in (Psalm 6:9 NKJV) “The Lord has heard my supplication; the Lord will receive my prayer.” Amen!”