Humm... Pretty sure we cant simulate all enclaves, and a 3 year long siege is impossible to simulate here. But maybe important enclaves could be linked to the capital? I mean "linked" like HoI2 provinces on both sides of the Himalaya mountains ('Impassable' province link), supplies can go through such links, but no unit movements between (no exploit like invade Bihac then go directly to Sarajevo). It would remove the need to add lots and lots of events to simulate siege, but allow a better simulation of supplies smuggle (not "realistic" but better than nothing).