I would be fine if a vassal was at -3 stab and just continued to churn out cores. This was routinely done in pre-Common Sense. Sure, killing 500k rebels in China over trying to feed all of Ming to Mongolia over 30 years is a bit rough but you gotta do what you gotta do.As an overlord, if your vassal has this disaster, just don't feed them. Why would you? I mean really, what are you thinking? The land they're given will come with unrest, the overextension will increase coring costs, the coring itself takes stab-raising admin points... you're just piling more problems on. Yeah, as I said, the AI probably needs a look at getting out of this disaster better, but frankly if you're shoving unrest-laden admin-taxing provinces onto a vassal with internal problems, you deserve what happens.
In this patch I've let a vassal sit 30 years with no additional fed provinces. It still was not able to get out of internal conflicts with admin 4 ruler and even teched adm from 14->15 instead of exiting the disaster. At that point its either annex the vassal as soon as they get the disaster, or feed them despite internal conflicts.
See, you've presented a false choice:
1) let them get out of internal conflicts
2) feed them more land
1 won't happen even if you don't choose 2.
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