If a team (country) has only 2 instead of three player, then ppl from for example USA can join another country if they have "roots" from that country. For example: parents are from Country XY or somebody was born in Country XY (but lives in Country AB), he can join Country XY.
If a team like Italy or USA have more than 3 player, then a small tourney can be played.
I think Scandinavia, BeNeLux, Alpine Countries,... can count as one country. I know only one person from Liechtenstein, and one from Austria and one from Swiss -> Team Alpine
other examples:
One from Norway, two from Sweden -> Scandinavia.
Two from the Netherlands, one from Belgium -> BeNeLux.
I know we have unfortunately too few ppl from Africa (I actually know just two), here I would say the continent counts as one "country".
The bigger problem is, that this is a pvp event and we'll need many many players from different countries to build enough and complete teams. I think the community is too small to realize this idea =/