Our game concept for Nato is not clear for now. How to portray them in game? Do you spawn units in the areas they went historically (with abstract airlift events)? But then how they get supplies and their supply lines? Give supplies by events? AI Nato or player playable? Not too crappy to get loads of 'free' stuff events for player?
IIRC supplies don't work on units in neutral territory, not sure if Military access allows supply passage or alliance is needed.
Also the situation is kind of the same with the pro-Serb units who rise up across Croatia and Bosnia. Same game "country"? Yes or no, units will 'appear' trapped behind enemy lines. In real life they get food from their local kinsmen but not in game, supply lines dont reach them.. So they would spawn and then auto die when enemy attacks them, because they are "out of supplies".
Both RSK and RS had control over most of the local police force and later got shield by JNA/YPA, Bosnia would allow military access to these regions in order for supplies from Belgrade to flow.
I think SFRY needs 'Federal troops' (mostly locked in place and released/removed by events)) all over the country (off-map supplies production to keep them alive) with military access by all republics to allow supplies to reach them, most of these units would be removed by events with Serbia inheriting what remains as historically did happen.
Canceling military access would leave these troops cut off allowing player a chance to attack them and capture large amount of weapons but with high risk of losing international support in the long run and possibly provoking much larger war but I got a feeling most players would prefer scenario turning into 'what if' total war anyway.