(12) The term “sibling” means an individual who satisfies at least one of the following conditions with respect to a child: (A) The individual is considered by State law to be a sibling of the child. (B) The individual would have been considered a sibling of the child under State law but for a termination or other disruption of parental rights, such as the death of a parent.
42 USC § 675(12)
None identified. Default scope is assumed to be the entire title.