Joannes Koopman, born 1778, Married to Marta Brunselaar born 1778 and died Jan. 3, 1810 in Amsterdam. Three children, Anna Elisabeth (1801) Catharina (1802) and Joannes (1807) That's all I have been able to find. Does anyone have additional information, especially parents for both Joannes and Marta?
Dear Harald, Jan Koopman came from Lathen in Germany. Searching in parish records in Germany is not that easy. In order to get further directions on how to approach that, I suggest to post a new question in the Duitsland subforum on Stamboomforum.
The name Brunselaar (Brunsler, Brunselar, Bruinselaar, Brunselaer, Bronselaar, etc) is also clearly of German origin, as the family name refers to the village of Bronslar. The name pops up at different places in the Netherlands [link] but none of those appears to be linked to Martha nor Bartha (suspectedly a sister of Martha). You might be lucky by setting up an extensive search but it is not simple.