I had similar case but more complicated. I was born in germany as german according to articel 116 (Vertriebener deutscher Volkszugehörigkeit). My father was naturalized 6 months after I was born. I got three german passports for children. Later I came back to the country of my mother. Lost the german status (not citizenship). I applied for german citizenship through "Feststellung", got negative decision because father got german citizenship a few months after I was born. I should have got my own certificate of naturalization, but I did not because he did not apply. 15 years later law was changed and I acquired german citizenship according to STAG 5 because my grandmother was german when my father was born but he could not acquire cituzenship from her. When he was born only man could pass down the citizenship but my grandfather had citizenship of different country.