deputize
verb
/ˈdepjutaɪz/ ukus(UK also deputise) [ T ]
to choose someone to officially speak or act in your place or for a particular purpose:
deputize sb to do sth The administration made a formal request to the Attorney General's Office to deputize an agency lawyer to handle all animal rights cases.
[ I ]
to act or speak for another person, especially at work:
I was asked to deputize for the Head of Administrative Law in a meeting.