Play them instead of all the friendlies they have now.
If there's 54 nation divided by 4 leagues, that's a lot of games.
I don't imagine they've worked out those details yet.
But maybe they'd just play one round if matches.
So 13 teams a league, 12 matches each. Not that many really
Each 16 team division is divided into 4 groups of 4 e.g 1A, 1B, 1C and 1D.
So if you play each team in your sub-division home and away that's 6 games.
The winner of each sub-division qualifies for the semi-finals and final played at a neutral venue to determine the league champion.