Hello Robert,
I am sorry but I do not have any information on my ancestor's 4th husband. All I have is:

My ancestor-Hans Jurgen SONNABEND who was living in Thielen, m. 2)13 Apr 1787, Catherina "Trina" BOCK born 1750; died 3 Aug 1815, St. Annen; dau. of Claus BOCK and Ann Elizabeth ADAMS.
Catherina m. 1) 1775, Thomas THOMSEN and had 1 son-Jacob; m. 2) 1783, Jacob Carstens-no children that I know of;
m. 3) Hans Jurgen [above] and had 2 children-[my ancestor] Thomas Jurgen and Hans Jurgen SONNABEND.
Hans d. 1792, St. Annen, so I assume that is where Catherina m. her 4th husband, 26 Oct 1793, Peter DAU.
I do not have any data on Peter, or whether they had children, as she would have been 43 at that time. I don't know if she married again, after burying 4 husbands!!
Thank you for writing,
Carol