For an institutionalized person 20 years of age and younger, who is neither married nor emancipated, the state of residence is:

1. (1) That of the parent or the legal guardian at the time of placement. If a legal guardian has been appointed and parental rights are terminated, the state of residence of the guardian is used.
2. (2) The current state of residence of the parent or the legal guardian who files the application if the person is institutionalized in the same state. If a legal guardian has been appointed and the parental rights are terminated, the state of residence of the guardian is used.
3. (3) The state of residence of the person or party who files the application, if the person has been abandoned by his parents, does not have a legal guardian and is institutionalized in the same state. Abandonment also includes deceased parents, as well as parents who desert their children.