Hi Liz and Philip,
In the genealogy part as well as the other links , it seems that in that area and during those days probably Willemsz (z = standing for zoon ,thats son in English, written that way it´s meaning son of Willem ) would be even more correct ,maybe you can add van Kouwenhoven as aka last name ??
So for all van Couwenhovens/Couwenhovens/van Kouwenhovens/Kouwenhovens from before 1811 (so all Kouwenhovens that were not officially registered in churchbooks or other registers with that name for official last name ) it would be the most easy to just use the patroniemsystem ,so if Jan has a known father named Willem ..his registered name by birth would most likely be Jan Willemsz. His father would be named Willem Jansz ,and so you go on ,girls also got the first name of father for last name ,for example if Jan would have a daughter named Sjoukje ,she would become Sjoukje Jansdr .
To make it easier for all people doing research I guess using van Kouwenhoven(or van Couwenhoven or even Couwenhoven/Kouwenhoven) as aka last name would be fine . If the children or greatgrandchildren of these persons were registered with Couwenhoven or whatever spelling of the name ,I would go by that name for the people (great/ great/ grand/parents etc ) from before the registration as aka . My guess is all lines of this branche used different spellings for the registration ,with or without the ´van´ ,and also Dutch names sometimes get spelled ´incorrect´ or Anglicised ...Gerrit sometimes spelled as Garret or Geret ,guess there are many duplicates now because of this spelling differences and of course also because of the use of so many spelling differences in the last name . Can imagine it getting very confusing for many ,so it´s great to see everyone is trying hard to get it all straight now .
here are some pictures from the farm also
Today I found this familydirectory http://freepages.genealogy.rootsweb.ancestry.com/~msw12041937/familydirectory.html
the whole familystory in English ,maybe you all seen or read it already but I´ll add it just in case . Geret must be Gerrit ,and Wolfert Geretse =Wolfert Gerritsz ,and Neeltje must be Jansdr ,here also the names are confusing for the writer it seems . also a Altje mentioned somewhere ,Altje probably would be Aaltje because thats a name commonly used in those days in the Netherlands.
And according to this directory , Wolfert Gerritsz (van Kouwenhoven) only had tree sons:1. Gerrit Wolfertsz (He most likely is named after his grandfather Gerrit)
3. Pieter Wolfertsz
Maybe this familydirectory can help unrafeling which people are duplicates and can be merged ? And of course to prevent the adding of children or other people ,who in fact are not children but attached to the van Kouwenhoven family in another way .