σε προσθέσθαι, “"to associate you with them (as a prospective ally) in the neighbourhood of their land, and not (to leave you) in a place where you will be your own master."” Cp. Her. 1.69 “χρήσαντος τοῦ θεοῦ τὸν Ἕλληνα φίλον προσθέσθαι,...ὑμέας...προσκαλέομαι φίλος τε θέλων γενέσθαι καὶ σύμμαχος”. With μηδ̓, etc., a verbal notion such as “ἐᾶσαι οἰκεῖν” must be supplied from “προσθέσθαι”: cp.
(sc. “καταστήσατε”). ἂν … κρατοῖς, nearly = κρατήσεις. See on “ἵν᾽ ἂν...εἴποιμεν”, 189. With the MS. κρατῇς, ἄν belongs to ἵνα: "wherever you may be your own master": which is evidently less suitable here.