Precautionary addendum was defined by statute in Domestic Relations Law § 114. The highlighted language from DRL § 114 is known as the precautionary addendum:

The foster parent or parents and the person adopted sustain toward each other the legal relation of parent and child, and have all the rights and are subject to all the duties of that relation, including the right of inheritance from each other . . . but as respects the passing and limitation over of real or personal property dependent under the provisions of any instrument on the foster parent dying without heirs, the person adopted is not deemed the child of the foster parent so as to defeat the rights of remaindermen.