There is literally no reason for the Tortun to hate each other, or at the very least not the northern ones.
When they came together under the republic, they became the most powerful and feared state on the entire continent.
It has required the strength of three other great powers and 2 secondaries in order to force them into a position where they aren't even decisively losing, just under duress.
You would have to contrive some truly incredible reasons to get the people of these states to actually hate each other when essentially five minutes ago they were united in camaraderie and the terror of Syffryn.
There are things you can brute force practically, and things you can't. Getting the Tortuns to hate each other is not one of those things.
During XX century it was possible to keep half of Europe as (mostly self-governing) puppets of Moscow. It's not 100% impossible (though we lack strong ideological justification like communism).
Ah yes under the steel hand of the Warsaw pact and after decades of indoctrination or death type political systems. Even so, there was still the Prague Spring and the Hungarian rising, which had the potential to unravel the entire system through domino effect had they succeeded. Also most of those states had ages long nationalistic problems with each other that Moscow could play off of each other. The Tortun Republic is a single nationality.
I'm not saying it can't be done, but do you actually want to use resources on that?
Sure happened after WW2.
And it was such for less than a generation. Before it was a bunch of dukedoms, so it can be split again.
Yeah, because there was actually such thing as France before the revolution. There was no Tortun before it.
Break it into nations, promote local culture, use the fear of Ochruhr return to bind them closer to their patrons, ensure they have a reasons to fight each other and need support and there won't be a Tortun after.
No, before it was the United Ueman empire, essentially a less dysfunctional HRE. The Tortun identity very much existed already and had for centuries.
For WW2, I addressed that above, and it required population transfers on a scale never before seen, and hopefully will never be seen again.
No one is going to care about local culture, at least not immediately, after they've seen what they could do together. Why would they want to get closer to their puppet master? The reflex of nationalism is to rebel and reform the nationstate, not huddle up to your warden.