Hi, I'm doing research on the family Posthumus from Harlingen. However, my gggrandfather left Harlingen in approx. 1824 and was the only child. I know that in Harlingen there was/is another family Posthumus. I haven't found out yet if my gggrandfather had relatives with the same surname. Cause: mandatory surnames from 1811 due to the decrete of Napoleon in 1811. A lot of people, especially in the northern provinces didn't have surnames yet (only patronymes). So it could be looking for a needle in a heystack (sorry: for you and for me).