Each group will then be split up into smaller leagues. In Groups 1 and 2, the teams would be split into 4 groups of 3. In Group 3, there will be 2 groups of 3 and 2 groups of 4. In Group 4 there will be 4 groups of 4. UEFA have yet to make it clear exactly how the make-up of these leagues will be decided, but I assume that it will be a simple seeded draw. Initially, the seeding will presumably be based on the UEFA coefficients, but in future tournaments it could instead be based on the league positions in the previous Nations League.
Assuming that is the case, the groups could look something like this: