surrogate

A substitute (usually of a person, position or role).

A mixture of horseradish and mustard often serves as a surrogate for wasabi.

A person or animal that acts as a substitute for the social or pastoral role of another, such as a surrogate parent.

A deputy for a bishop in granting licences for marriage.

A politician or person of influence campaigning for a presidential candidate.

A judicial officer of limited jurisdiction, who administers matters of probate and intestate succession and, in some cases, adoptions.

Of, concerning, relating to or acting as a substitute.

To replace or substitute something with something else; to appoint a successor.