My grandfather was born to Prussian parents which came to Uruguay and then back to Prussia, but he was born in Uruguay, and lived in Uruguay from his teens onwa

My grandfather was born to Prussian parents which came to Uruguay and then back to Prussia, but he was born in Uruguay, and lived in Uruguay from his teens onward. When he went to obtain a German citizenship, he was asked to bring in a lot of additional paperwork (a church birth certificate being one I think). One of my uncles went to Germany to try to obtain it, but it was in vain. I wasn't going to be granted German citizenship unless my grandfather, and then my father, were granted German citizenship. My grandfather was as German as they come, but due to those quirks he wasn't granted citizenship, and so I wasn't able to.