We understand that you're going through a challenging time, and we're here to support you in prayer and counsel. Let's first address the spiritual aspect of your situation. It's wonderful that you ended your request with "In Jesus Christ's name. Amen." This is so important because, the Word of God says, "For there is one God, and one mediator between God and men, the man Christ Jesus" 1 Timothy 2:5 WEB. He is the one that makes our access to God possible.
In times of stress and trouble, God encourages us to cast our anxieties on Him because He cares for us 1 Peter 5:7 WEB. Let's pray together for your situation:
Heavenly Father, we come before You in the name of Jesus Christ, lifting up our sister who is in need of Your divine intervention. We pray for her healing and strength, that she may be able to walk and lift items as she did before. We ask You to soften the hearts of her family members, especially her mother and sisters, that they may treat her with love, kindness, and understanding, as Your Word instructs in Colossians 3:12-13 WEB, "Put on therefore, as God's chosen ones, holy and beloved, a heart of compassion, kindness, lowliness, humility, and perseverance; bearing with one another, and forgiving each other, if any man has a complaint against any; even as Christ forgave you, so you also do".
Lord, we also pray for her sister, that You may convict her heart to speak kindly and positively, and to be more grateful for the help she has received. We pray that she may consider her ways, that You will turn her heart towards wisdom as you did for Solomon in 1 Kings 3:9 WEB. Show her the importance of disciplining her children as Proverbs 23:14 WEB, instructs us not to withhold discipline from a child; if you punish them with the rod, they will not die. Punish them with the rod and save them from death. We rebuke the spirit of mockery and pride that is causing her to ridicule her sisters and brag about her own life. We also pray that she may find it in her heart to move back to her own apartment, but before this, we pray that any disputes regarding the lease are resolved peacefully and justly.
Father, we also pray for provision for our sister, that You may open doors for her to have her own home in due time. We ask that You surround her with godly friends and family who will support and encourage her in her time of need, being a true family to her in this time of difficulty.
Lastly, Lord, we pray for her sister's children, that they may learn obedience and respect for their elders, and grow in the fear of the Lord. We pray that our sister may be able to help her sister with her youngest nephew as she regains her strength, and that her sister may be understanding and patient during this time.
We ask all these things in the powerful name of Jesus Christ, our Lord and Savior. Amen.
Regarding your sister's comments about husbands and children, remember that God has a unique plan for each of us. While marriage and children are blessings, they are not the only measures of a fulfilled life. The Apostle Paul encourages us in 1 Corinthians 7:32-34 WEB that he would have them to be free from cares. He that is unmarried is concerned for the things of the Lord, how he may please the Lord. But he who is married is concerned about the things of the world, how he may please his wife. There is also a difference between a wife and a virgin. The unmarried woman cares about the things of the Lord, that she may be holy both in body and in spirit. But she who is married cares about the things of the world--how she may please her husband.
Keep focusing on your relationship with Jesus Christ, and He will guide your steps. Psalm 37:23 WEB says, "A man's goings are established by Yahweh; and He takes pleasure in his way."
Stand firm in your faith, and remember that God is working everything out for your good because you love Him and are called according to His purpose Romans 8:28.
Prayer Focus: God, Thank You for loving me. God, I ask You in Jesus’ name please bless me with everything that I stand in need of and everything You want me to have. 
