If you can't beat them, join them.
and If you can't lick 'em, join 'em.Prov. If you have to give up fighting some group because you can't win, band together with them. (The version with lick is informal.) Jill: I just got a kitten. Jane: I can't believe it! You used to hatepeople who owned cats. Jill: If you can't beat them, join them. Alan: I hear you're a Republican now. Fred: Yeah, I figured, if you can't lick 'em, join 'em.