A more thorough explanation:

A quasi-guardian is a person who assumes the role of a guardian without any legal authority. This person may be made to account as a guardian.

For example, if a person takes care of a child without being appointed as a legal guardian, they may be considered a quasi-guardian. If the child's parents or legal guardians were to question the person's authority, they may be required to prove that they acted in the best interest of the child and had the right to make decisions on their behalf.

Another example of a quasi-guardian is a person who is appointed as a standby guardian. This person is designated by a parent to assume responsibility for a child at a future date if the parent becomes incapable of caring for the child. Until that time, the parent retains custodial rights, but the standby guardian may act as a quasi-guardian in certain situations.

In both examples, the person assumes the role of a guardian without the legal authority to do so, making them a quasi-guardian.