In my MSc class today, we were asked to work on a case study to amalgamate two offices.
It was interesting to see how complicated people made the whole thing. Multiple communication techniques and strategies, loops, groups, etc - arrows everywhere!!
As someone who has been involved in moving people to different locations and merging functions, I found the best thing to do was to keep it all very simple, open and honest.
I focussed on the idea of trying to get everyone together, briefing them together, (briefing from the "big boss" about the grand vision) then breaking up into small groups to discuss strengths, weaknesses, opportunities and threats - then collating the ideas so that they could be fed back into the centre.
From there, it was about picking the best ideas, communication of the way forward and dealing with threats to the project. Obviously there will be people who think that this is a bit of utopian view, but it does work well in practice.