In heir apparent (and its imitations): Manifest, evident, obvious; applied to a person who will undoubtedly inherit, if he or she survives the…

Put by devious means in the place of another; fraudulently substituted for the genuine thing or person… spec. Of a child, esp. one set up to displace…

= reversionary, adj. 2. Obsolete. rare.

Of a person: entitled to the reversion of something. Chiefly in reversionary heir.