temporary expedient

Band-Aid

expediency expedient improvisation makeshift recourse refuge resort resource shift substitute

pis aller

permanent

permanency solution

backup replacement stand-in surrogate

agent alternate assistant auxiliary changeling delegate deputy double dummy equivalent expediency expedient fill in ghost locum makeshift procurator proxy recourse refuge relay relief representative reserve resort resource standby stopgap sub succedaneum successor supplanter supply symbol temp temporary understudy vicar

dernier ressort ghost writer locum tenens pinch-hitter

being entity permanent