Doesn't look like a connection. The earliest Zwart ancestors we are able to find are from the area of Driever, Germany, just across the border from Groningen. They were in the area of Beerta, and Midwolda, Groningen, in the 1700's. Willem Geerts Zwart 1795-1848 is our direct ancestor. Uithuizen is pretty far North of there but not unlikely that they were related. I did find an Ekke Zwart born 20 Oct 1849 in Uithizen whose parents were Jan Harms Zwart and Janna Jans van der Molden. Also found the parents marriage on 12 Feb 1842. Ekke Zwart son of Jan Harms is listed as married on 18 Apr 1891 in Uithuizen to Geertruida Swijgman. Ekke age 22 was married to Pieterke Werkman on 22 MaY 1907 in Uithuizen. Looks like Ekke born abt 1850 died 23 Jan 1924. You likely have this info. If not, it can be had at genlias.nl You can contact me at ralphdelange@hotmail.com