Like right now in reality in the south China Sea where you sometimes have 3 countries disputing a territorial claim and lets pretend we had an alien attack in that area and blustery politics means that you would get more points for responding to these types of missions.
Another scenario is observer confusion... so ee could also look at it like this... so let's say you have a ufo that that Flys along the Bosphorus on the European side. Could observers be able to identify at range that it was on the European side or Asian side? I'd say that it's close enough to count for both.
thoughts?
I know this is weird, but since their is no mission spawning, as far as I understood it in overlapping regions... it's a touch moot.... unless I misunderstood.
There are already a few vanilla countries that fit this description. While the Geoscape displays the correct US-Canada border, in reality in some areas like the Great Lakes both countries have areas overlapping. So any Alien/XCOM activity there will be counted both for the US and Canada
The areas of the countries are only used for scoring/funding proposes. Regions are used for spawning alien missions and you can basically spawn everything you want in any place on the globe.
EDIT: Just to further my last point, you could have 3 different factions, like the PRC, Vietnam and Philippines and each have their own missions over the South China Sea. The main issue with this idea would be that they would all generate negative score for the player, even from Chinese craft overflying the PRC's territory, or you could set flyovers to generate no score at all, but that would go against your original idea.
