We are truly sorry to hear about the struggles you and your family are facing, Maria. We will stand with you in prayer and offer some biblical encouragement.
Firstly, we commend you for acknowledging Jesus Christ as your God, that is the first step to having access to God. Jesus saith unto him, I am the way, the truth, and the life: no man cometh unto the Father, but by me. As we approach God we should acknowledge we are doing so in Jesus name. The disciples were first called Christians in Antioch, because there is no other name given for salvation. Therefore we will pray to God the Father in the name of Jesus Christ.
Let's address the concerns you've shared using scriptures from the World English Bible (WEB).
Regarding unbelief in your daughter, remember that God is patient with us all. Peter 3:9 says The Lord is not slow to fulfill his promise, as some count slowness; but is patient with us, not wishing that any should perish, but that all should come to repentance. Also, At Romans 12:18 it says If it is possible, as much as it is up to you, be at peace with all men. It is heart breaking when there is a lack of peace in your family but continue to be a testimony to your daughter about the Grace of God.
Regarding your husband it says at Ephesians 5:25 Husbands, love your wives, even as Christ also loved the assembly, and gave himself up for it; It is important to be a good example to your daughter with your marriage. From the context of your request, it is not clear if he is a believer or not but it is incumbent on you to trust God and follow scripture.
Concerning your health, God promises us in Romans 8:28 We know that all things work together for good for those who love God, to those who are called according to his purpose. This should be a comfort in your current circumstances. If God allows something to occur, even if it appears to be bad, it is to accomplish a purpose.
Regarding your nephew, we pray for God's protection and intervention. Remember the promise in Romans 8:38-39 For I am persuaded, that neither death, nor life, nor angels, nor principalities, nor things present, nor things to come, nor powers,nor height, nor depth, nor any other created thing, shall be able to separate us from the love of God, which is in Christ Jesus our Lord.
Let us pray together:
Heavenly Father, in the name of Jesus Christ, we come before you, lifting up Maria and her family. Lord, we ask that you soften the hearts of her daughter and husband, reconciling them to Yourself and to the family. Grant them the spirit of forgiveness and understanding, that peace may reign in their home.
Father God, we also ask for Your healing touch upon Maria's health. Guide the hands of the medical team that will attend to her, and let Your will be done in her life and in her unborn child.
Lord, we also plead for the safety and release of Maria's nephew. We ask that you intervene in this situation and let your justice and mercy be evident.
Finally, Lord, we ask for Your peace to fill their hearts, knowing that You are in control of all things. In Jesus Christ name, we pray. Amen.
Stay strong in faith, Maria. Trust in the Lord with all your heart, and do not lean on your own understanding. In all your ways acknowledge him, and he will make straight your paths. Proverbs 3:5-6