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