The number of patricians houses (trade privileges) that I can have on an island = 60% of the number of citizens houses on that island + number of envoys worldwide/110 (improvable by certain attainments). Suppose I have 550 envoys on my oriental island. Does this mean I get 5 additional trade privileges in each of my occidental settlements or if I use 3 on one occidental island I will have only 2 remaining for the other?
If no-one answers this definitively, eventually I will (by trying), but since I currently only have one occidental settlement, I wanted to know beforehand to plan my next settlement.