συμπρεσβεύω
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 to be a fellow-ambassador, be joined or associated with on an embassy, D.19.189, Aeschin.2.169, IG22.844.15, OGI333.12 (ii B.C.):—Med., join in sending an embassy, Th.3.92, 5.44.
German (Pape)
[Seite 990] Mitgesandter sein, mit bei einer Gesandtschaft sein, οὐδὲ συμπεπρεσβευκέναι φημί σοι Dem. 19, 189, u. A. – Im med., Thuc. 3, 92. 5, 44.