This is a thought that I have been tackling for quite a while now, but in the event of a country or region undergoing decolonialization, how should settler populations, especially multigenerational populations, be handled?

For example in the example of Israel, once the nation is reestablished as a one state Palestine, what would happen to the settler population? Especially those that aren't living or participating in illegal settlements or exploitation?

This question is complicated farther by multiple generations of people who were born in a location and have no ties to any other country or location. Those people don't have anywhere to go and can't be "sent back" to where they came from as they have no ties. For example if a person's grand parents immigrated decades ago to a country as settlers, and then their children and then grandchildren were born and lived their whole lives in a location, what would you do with those grandchildren? You can't just throw them back to the country their grandparents were from. This question is made even harder when the generations start spanning back much farther.

Another problem that I am running into is that many solutions including "leftist" ones essentially boil down to ethnic cleaning even if they do not say it outright. Or they completely ignore the question or resort to some fantasy scenario where the settlers magically disappear or all agree to move.

So how should these populations and people be handled?