When FMG releases its combat unit pieces (which, if I’m not mistaken, will include some sort of Leader unit), I suppose a house rule could be devised saying that you can only talk to the players on your side when all your Leader pieces are in the same territory – for instance, the way Roosevelt, Churchill and de Gaulle met at Casablanca after the Allied invasion of French Morocco, or the way Hitler, Ciano and Kurusu signed the Tripartite Pact in Berlin. There could also be a rule saying that you can only talk to the players on the enemy side when all your Leader pieces are in the same territory – an early example of which in the game would be the French surrender in June 1940. :-D