Build Positive Team Dynamics
While communicating outside the team is essential, internal team communication is equally important. Honesty, respect, and trust are fundamental in cross-functional teams, even more than in departmental teams.
Team members often have to compete for organizational resources, so when you ask them to work together, spend sufficient time building trust and creating an environment of open communication. These people are also likely to be very diverse in the way they think, analyze, and solve problems. If you build trust between them, then they will be much more likely to contribute freely and openly to discussions, even when they know their ideas won't be popular or agreed with.