§1. The place of origin of a child, even of a neophyte, is that in which the parents had a domicile or, lacking that, a quasi-domicile when the child was born or, if the parents did not have the same domicile or quasi-domicile, that of the mother.
§2. In the case of a child of transients, the place of origin is the actual place of birth; in the case of an abandoned child, it is the place where the child was found.
Source: Code of Canon Law (Vatican.va)