Please cite the principle of international law which requires the present day iteration of a state's government to have had past administration of a breakaway territory in order to assert a claim of ownership over said territory.
Please also cite any supporting state practice and opinio juris.
Taiwan is not a part of the PRC, de facto or de jure. Say that Taiwan is a part of China all you want, but it never has been a part of the PRC.
The German Democratic Republic was never part of the Federal Republic of Germany either. Until it was.
What a completely irrelevant exercise in pedantry.
The truth, like it or not, is that PRC has never, ever seized control of Taiwan. Hopefully it never does. This is not pedantry.
Please cite the principle of international law which requires the present day iteration of a state's government to have had past administration of a breakaway territory in order to assert a claim of ownership over said territory.
Please also cite any supporting state practice and opinio juris.