term:

Substitution

substitution n

: the substituting of one person or thing for another: as
a in the civil law of Louisiana
: a disposition not in trust by which a donee, heir, or legatee is charged to hold property transferred and return it to a third person compare fidei commissum, vulgar substitution NOTE: Substitutions are prohibited.
b : replacement of a party to an action with a successor or representative upon motion to the court when the party is unable to continue litigating (as because of death, incompetency, transfer of interest, or loss of the office for which the party was suing or being sued in an official capacity)
c : the replacement of a new agreement or obligation for an old one see also novation
sub·sti·tu·tion·al [-shə-nəl]
n

sub·sti·tu·tion·ary [-shə-nər-ē]
adj

Source: Merriam-Webster's Dictionary of Law ©1996. Merriam-Webster, Incorporated. Published under license with Merriam-Webster, Incorporated.