Just use the normal rule that people arent allowed to swap nations like many did in last NWWC, just make them play for the nation they first played for / everyone knows ppl are from there and dont make weird alliances
and dont accept people saying a team is impossible without checking it yourself, cuz it mostly is (hello Spain and Ireland), its just their massive egos that dont want to play with worse players
U just keep losing possible Teams cuz of stupid stuff, like Red not being forced to play with SAU in last NWWC (which probably wont exist this time but u get the point)