udruživati

1. (udruživati se) to join forces; to team up; to unite
   Mali proizvođači se sve češće udružuju. — Small producers are increasingly joining forces.
   Stanari se udružuju da bi zajedno rešili problem. — The tenants are teaming up to solve the problem together.
2. (+ acc.) to unite; to pool; to combine
   Na ovom projektu udružujemo znanje i iskustvo. — On this project we are pooling our knowledge and experience.

The partner is expressed with s + instrumental: udruživati se s nekim.