Answer:
adoption
Explanation:
Adoption is the permanent change in the parenthood of a child. It legally transfers all the rights privileges and responsibilities from the biological parents or guardians to new parents. While the method of guardianship to a child's responsibility is not legally bounded, adoption refers to a permanent change in the parenthood of a child.
As per the question, The girl's aunt who is ready to take the legal custody of the child from the young couple is a perfect example of adoption.