Loretta-Marie, you state that "Elizabeth's parentage is not at issue here." Why not? Is it certain that Elizabeth's mother was Elsje Earle? Could Elizabeth Demarest have been a daughter of Jan Demarest (bpt. 11 May 1701) by an unknown first wife? Elsje Earle was married to George Simmons on 24 May 1729 (Hackensack Dutch Church)and son David Simmons was baptized there only a month later (3 Jun 1729). This implies that Elsje Earle would have married Jan Demarest sometime after 1730 in which case Jan Demarest would have been in his thirties when marrying for the first time. Is it not plausible that Jan was married previously, just as Elsje had been? Could Elizabeth have been a child of that earlier marriage, therefore opening up room for her to have been born maybe as early as 1725, which in turn would give her the room to have had son James Browning born as early as 1745?
I'd be interested in your thoughts, because when I first saw this proposed ancestry for Barack Obama, I pretty much had the same concern you've expressed, "the dates don't quite fit." What I've written above pretty much describes how I tried to work with this problem, and is pretty much how I've addressed it on my website http://freepages.genealogy.rootsweb.ancestry.com/~brouwergenealogydata/index.htmhttp://freepages.genealogy.rootsweb.ancestry.com/~brouwergenealogydata/index.htm (look up Elizabeth Demarest or Elsje Earle in the index then click on the name).
If I can find clear evidence that Elsje was certainly Elizabeth's mother, I would need to alter my theory. Thanks.