I am Andreas' (Andrew in English)Rosentreter's great-great-granddaughter. I have that he was born in 1845 in Abrau. But, I do not have a brother Conrad in his family. I am assuming this is the same man that you are speaking of. I don't know, but Abrau, from what I understand was extremely small. His parents were Joseph (maybe Josef) Rosentreter and Anna Katarzyna Musolf. Please let me know if he is the same person you are looking for!!