ἀντιχρηματίζομαι
From LSJ
Ζῆν οὐκ ἄξιος, ὅτῳ μηδὲ εἷς ἐστι χρηστὸς φίλος → Life is not worth living if you do not have at least one friend.
English (LSJ)
A transact business instead of another, PFlor.382.59 (iii A.D.).
Spanish (DGE)
actuar en nombre de otro, representar, PMich.529ue.49 (III d.C.), cf. PFlor.382.59 (III d.C.).