2. (Law) The sending or placing back of a person to a title or right he had before; the restitution of one who obtains possession of property under a defective title, to his rights under some valid title by virtue of which he might legally have entered into possession only by suit. --Bouvier.
This is the Dictionary.com definition, so it would refer to unknown people who might have a legal claim. I believe that Paul Getty left fifty dollars of something to any children that he didn't know about so that if anyone came out of the wordwork claiming to be his child, that's all they'd get. I presume this is a case of this.
