The most plausible path forward I see is the Native American model from the USA.
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Genocide and ethnically cleanse the target population into progressively smaller reservations. (Israel is here)
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Sign treaties recognizing the target population as a sovereign entity existing within the borders and legal framework of the parent nation.
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targeted population demilitarized. It's people become increasingly integrated into the parent nation.
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Civil rights movement for members of the targeted population within the parent nation.
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Develop an esoteric field of law clarifying what "sovereign entity existing within the borders and legal framework of the parent nation" even means.
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Gradually chip away at the targeted population through a combination of progressively narrowing the scope of law covered in (5), and the natural integration of the targeted population into the host population (US is here)