Ok, this is crazy. I think that the Nicolaes Groesbeek that married Angenietje de Wandelaer, was a different man than the one that married Marytje Quackenbosch, and was instead the son of Johannes Groesbeck and Geertruy Quackenbosch.
Johannes and Geertruy baptized a Nicholas in 1710, which would make him about the right age to marry in 1732, as the age of consent for the New Netherlanders was 25. The marriage doesn't mention him being a widow, though at this point in the church books all of the marriage records were very brief.
* 1732 15 May B. Nic. Groesbeek and ___ d. Wandelaar.
The first child that Nicholas and Angenietje baptized was a 'Hannes' and the witnesses were 'Hannes' Groesbeek and Geertje Quackenbos.
* 1733 May 27 Hannes, of Nicolaas Groesbeek and Agnietje De Wandelaars. Wit.: Hannes Groesbeek, Geertje Quackenbos.
Then I think the first Nicholas, widow of Marytie Quackenbosch, went on to marry the daughter of Benoni van Curler, son of Arendt van Curler, which makes sense because it does appear that Nicholas' mother was a Schuyler. The van Curlers and Schuylers were of the same class in New Netherland. How a Quackenbush got in the mix, I don't know. :> (Acutally Benoni's wife, Elizabeth van der Poel, may have been related to the Quackenbosches through the van Starrevelts...) This Nicholas was also born before records begin in Albany (1683) so for him to still be having children in 1745 would be somewhat unusual. Possible, but unusual.
The reason that I think this is because I just got a batch of DNA cousins who descend from Nicholas Groesbeek and Angenietje de Wandelaer's son Harmen, and the connection makes total sense if Nicholas was a Quackenbosch descendant, the other Nicholas only being connected by marriage. The suspicion of conflation was already there.
Edit: This is telling. Jr. means that his is being used to disambiguate him from an older Nicolaas.
* 1737 Mar 02 Harmen, of Nicolaas, Jr., and Agnietje Groesbeek. Wit.: Hannes and Rebecca De Wandelaar.
Additionally, "Nicolas Js. Groesbeck was buried on 30 Jun 1746", right after the baptisms for Agnietje end.
Edit edit: all that and apparently this has already been figured out http://freepages.genealogy.rootsweb.ancestry.com/~rclarke/page1/groesbec.htm
And the DNA cousins descend from both Nicholaases.