Sui generis
A similar case that led to the use of the label "sui generis" is the relationship of New Caledonia relative to France, because the legal status of New Caledonia can aptly be said to lie somewhere between a French overseas collectivity and a sovereign nation. Although other examples of such status for other dependent or disputed territories may exist, this arrangement is unique within the French realm.
Surrogacy
Traditional surrogacy (also known as partial, genetic, natural or straight surrogacy) involves natural or artificial insemination of a surrogate. If the intended father's sperm is used in the insemination, then the resulting child is genetically related to the intended father and genetically related to the surrogate. If donor sperm is used, the resulting child is not genetically related to either intended parent but is genetically related to the surrogate.