Philippians 4:2 KJV
I beseech Euodias, and beseech Syntyche, that they be of the same mind in the Lord.
Sisterhood is about partnering to take of God's children together. The children of your sister are supposed to find great inspiration, love and comfort from you. A chosen lady's fears about what could happen to her children when she is no longer there should be very minimal. Choose to become a sister! Becoming awesome and working at turning out great in life and ministry, just so you can be a good team player with your God-elected sister and so that many of God's children can find great comfort in looking up to several look-alike mother figures- that's an absolutely fantastic vision the Lord sets before you, when you are a chosen lady by God!