I find the system a bit weird. Seems to work under a system of chosen/favourites + randoms.
Lets say that I pick Lord Markinn as my Sovereign and head to the new game screen:

With those settings I decide to Customize Opponents and see:

I change my mind about Markinn and go back to pick Relias as my Sovereign. After that, back to Customize Opponents:

Hmmm So I lose one opponent? So now I'll play a Large map against two opponents instead of three, if I don't add any more opponents? In any case, I change my mind and go back to select Ceresa as Sovereign and then back to Customize Opponents:

Oook. Does it really mean that I would only fight an opponent? (I miss a Reveal Map cheat for the beta) Does it means "The chosen ones plus randoms"? In any case, I change my mind and go back to pick Procipinee as my Sovereign.
Now, when in the "WHere are you?" screen I can do two things:
Option 1.
Back to Customize Opponents:

There are no opponents!!! So all random then? Well, the answer must be not because you cannot close this window unless you have selected at least one opponent:

True Story.
So you pick an opponent and then start the game.
Option 2.
Hit Next to start the game without checking Customize Opponents. You start playing normally and the game doesn't end when you hit the first End of Turn, which means that there are opponents. So I quit and restart the experiment.
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Lets say that I picked Carrodus as my last Sovereign and started a new game knowing that the Customize Opponents list would be empty (aka Option 2). If I start a new game and go to the Customize Opponents I find:

Hey! The game added all those as my deault opponents in my last game for my Large map?
If I done all that again (Option 2.) but for a Small map, when starting a new game I get:

So the game added the needed opponents for a map of that size? Is that?
...
Why cannot I enter the Customize Opponents screen and leave it with "Selected Opponents" emptied? Why not a "Randomized Opponents" option? Why did I create this thread anyways?