act in concert, act together, affiliate, ally, amalgamate, associate, band, band together, be in league, club together, coact, coalesce, collaborate, collude, combine, concert, concord, concur, confederate, consolidate, conspire, cooperate, do business with, federate, fuse, get heads together, get together, go partners, hang together, harmonize, hold together, hook up, join, join in, join together, keep together, league, league together, make common cause, merge, partner, play ball, put heads together, reciprocate, stand together, team up, throw in together, tie in, tie up, unite, unite efforts, work together