I really REALLY don't like how much free will the story progression gives to inactive households. An unhappy marriage for the money was immediately split up, with the kid and the father completely disappearing from the town as soon as i switched to a different household for example.
On the other hand the EA story progression also allows for a bit too much freedom.

So i was looking at StoryProgression not to make even more grand moving and marriage changes, but LESS.
Is this doable?
Maybe some sims progressing in their career, making new friends or enemies, maybe having kids maybe not, but not splitting up their family, especially not when the family is still small, or god forbid moving out of town or something.
I have tried setting this up, but that disabled basically all interactions on the active lot as well.

The caste system was too much for me to really understand, and i ended up setting up..... something, where now plumbots even in the active household can't move out for example, even though the active household is set to allow those actions.

You can absolutely shut down almost any kind of progression you want via StoryProgression either at the town level or something more specific. Castes are the most common way to manage this, but you could instead set up lot, household, or sims settings however you want. For your purposes though, it sounds like it might be easier to set up one caste that doesn't allow any of the progression you're trying to prevent, then take your active household out of that caste while you're playing it so you can manually control everything.

You can find a couple of suggestions for caste settings here:

Story-Progression-Rotational-Caste-Settings

When I set up SP, I used igazor's approach and I think also disabled a couple of additional settings, then put all the sims I thought I might want to play into that caste using the household options as described. I left notifications on so I'd find out when anything odd happened, and the few surprises I saw were easy to fix and prevent in the future.

SP should prevent emigration by default.

Isn't there the Active Household Caste? I honestly don't want to bother setting everything up manually, and that sort of stuff that you linked is precisely what i couldn't wrap my head around.
Honestly i might just go back to EA progression and disallow story progression, because that has come the closest to what i actually want.
SP has been super unintuitive so far.

In that post igazor says that it's impossible to freeze other households, while you continue playing yours, but... isn't that exactly what disabling story progression under unmodded EA progression does?

The whole point of StoryProgression is that it's almost endlessly configurable, but then you have to configure it to your liking. Or you can configure it to someone else's liking and adjust from there, which is what I was suggesting with the link. Instead of thinking through each decision, you'd just go down the list and copy the provided settings, then adjust after the fact whenever you saw something happen that you didn't like.

It's impossible to freeze other households in that you can't make them stay home and do nothing. But you can prevent them from gaining any skills, romantic relationships, celebrity points, levels at work... most of what you might want here.

With no NRaas SP and EA story progression disabled, you'll still likely see emigration when the game decides that a household or the town is too full. This may or may not have anything to do with the total number of sims present.

Emigration is more likely to happen under EA control, as it is by default turned off in NRass SP. With EA it moves them and completely deletes them.

Well then which should i pick?
That's the issue, because there are always multiple options but none of them seem to have the same stuff as EA progression with basically all interactions with neighbors and on the given lot being possible, but nothing like emigration happening.
This is why me not being able to understand the settings is an issue, because i can't determine which group of settings would fit.

I basically want exactly EA settings with everything being available on the active lot, and default EA things being available for interacting with inactive people, but no emigration, and preferrably no moving out.

Emigration is disabled by default with StoryProgression. As long as you don't enable it, you're fine.

For moving, click on City Hall, select NRaas > SP > Town Options, and set Household: Allow Move as Family and Household: Allow Move Solo to false.

I originally thought you wanted more control, in which case a premade set of options would be useful. But if you really just don't want sims moving around on you, the above will work. I'd also suggest running SP on the Snail speed though, at least at first. The option is under NRaas > SP > General Options > Adjust Speed. This won't affect what SP allows sims to do, just how quickly it makes things happen.

I don't really understand. Default SP makes a boatload of things that i never had happen without it. Like career changes.

I don't want anything to happen, but i want all interactions to be possible with every sim. How do i do that?

Okay folks, I'm going to step in here so that hopefully we can move this discussion towards closure.

We do not offer a mod that stops emigration but otherwise causes the game to act exactly as is does under EA control (with or without progression). It might help to define what progression actually means -- it's not about free will or just about interactions, it's about sims other than active household being pushed to move forward or backwards in their lives in meaningful ways. Those ways include relationships (friendly and romantic), skills, finances, careers, celebrity status, having or adopting and raising kids and pets, etc.

These elements of progression are totally controllable under the SP mod, somewhat controllable under the AwesomeMod (our "friendly competitor") way of doing things, not at all controllable the EA way. To be perfectly fair, the EA control way with or without story progression wouldn't be so bad if it actually worked the way we all believe it was meant to -- leave the households pretty much alone when it comes to progression and where they live if they have been played actively at any point by the player, for the others emigrate some households out and bring some new ones in every so often to keep things fresh. It never does work right, instead it gets stuck in "OMG, this world's population is too high or out of balance" mode for whatever unknown reasons and tends to destroy the town's population over the course of a few generations leaving the player frustrated over losing the inactives they wanted to watch over and play around and leaving the one currently active household living in a ghost town with essentially no one left in town around them. Hence the popular desire to replace EA control with something else.

We cannot separate the emigration functions including its blocks on the same out from the rest of the mod any more than we can separate out SP's genetics or money systems. But the OP has repeatedly told us here and on other threads that they do not want progression. Trying to switch off all of the progression related things the mod in hopes of getting it to behave like EA control but still stop emigration is not going to be successful; SP is not the mod they want. And we shouldn't try any further to convince anyone that embracing progression with full control is a really fun way to play if they just don't like it, I've learned that the hard way with other players over the years.

Conclusion:
I don't think any of us realized it right away because this talk of free will and interactions was confusing to us, but Shimrod's EA Progression XML mod might be more of what they were looking for.

Wait.... really? Story progression doesn't disable emigration?

I also am aware that progression with full control can be a fun way to play but i absolutely can't figure out how to control the progression the way i want to, and having no progression is certainly better than finding out that the way i set things up meant that half the town is now empty, or that my active household can't do romantic interactions any more either.