We are truly sorry to hear about the situation you're facing with your sister. We will stand with you in prayer and offer some biblical guidance.
Firstly, it's important to remember that God calls us to forgive others as we have been forgiven. Ephesians 4:32 says, Forgive one another, even as God also forgave you in Christ. This does not mean that what your sister is doing is acceptable, but rather that you should harbor no bitterness or resentment towards her.
However, forgiveness does not mean that you should not seek justice. It is right to want your belongings returned, and it is appropriate to involve authorities if necessary. The Bible tells us in Romans 13:1-4 that God has instituted governing authorities to uphold justice.
We must also remember that God hates deceit and theft. In Proverbs 6:16-19, it is written, These six things Yahweh hates; yes, seven which are an abomination to him: haughty eyes, a lying tongue, hands that shed innocent blood, a heart that devises wicked schemes, feet that are swift in running to mischief, a false witness who utters lies, and he who sows discord among brothers.
Let us pray for you:
Dear Heavenly Father,
We come before You today in the name of Jesus Christ, lifting up our brother/sister who is facing this difficult situation. We pray that You would soften their sister's heart and convict her of the wrong she has done. We ask that You would bring to light all deceitful acts and grant our brother/sister favor in recovering what has been stolen.
We also pray for their reputation, that it would be restored and that they would be vindicated. We ask that You would surround them with Your peace and guidance during this time. Help them to forgive, even as they seek justice.
We pray for all those involved in this situation, that they would be caught in their wrongdoings and brought to justice. We ask that Your will be done in this situation, and that ultimately, it would bring glory to Your name.
In Jesus' name, we pray. Amen.
Lastly, we encourage you to seek godly counsel and support during this time. 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.
God's grace and peace be with you.