Sorry it's been a couple of years or so since I last booked one of these, so need to refresh my memory on the rules...

If I buy a xONE4 originating in 'Europe' , fly over to Asia, on to North America and transit directly to South America where I use up my 4 segments allowance, could I then buy an additional segment to go to Mexico (classed as N America) before heading back to Europe or is this counted as entering N America twice? (ie only solution is to buy an additional continent and to fly to S America from Australasia?)