Martha Gannung is not the daughter of John II and Sarah Denman of Newtown, Long Island, NY.
John and Sarah Denman had 3 sons only, with no daughters on record that I'm aware of. No daughters at all were mentioned for John and Sarah in the "Denman Family History".
Furthermore, Martha Gannung was born ca. 1669 in Flushing, NY. Her "brother" John (husband of Mary Gano) was born in 1643 in Newtown (and/or immediate vicinity), NY -- where the John Denman families always lived on their homestead, the entire time while residing in NY. Does anyone really believe they were born 26 years apart from the same mother? That is practically impossible.
Furthermore, whoever did this has also publicly made statements on Findagrave claiming that Jeremiah Genung/Gannung (Martha's husband) is the "Jeremiah Gannugh" brother-in-law in John Denman III's will. This simply cannot be true, if Martha is not John's sister.
But Mary Gano did have a *brother* (not in-law), Jeremiah Gano/Ganugh (although not married to some fantasy "Martha Denman"). Can you imagine two siblings marrying two other siblings? She marries the brother while her brother marries his sister? That would be a rarity, but in this case it simply didn't happen.
And early genealogists -- and family -- had every good reason to believe that the daughter of Francis Gano was indeed the wife of John Denman III. If she was not his wife, then whose wife was she? And if that was not Mary Gano, and her brother Jeremiah Ganugh, mentioned in John III's will -- then who were they? I can tell you that Jeremiah Ganugh was not married to John III's fantasy "sister".
So there is no basis for claiming any "confusion" surrounding Mary's maiden name. And family tradition emphatically refutes that baseless theory. Furthermore, Genung/Gannung just does not phonetically sound like Gano/Ganugh (the final G is silent in the latter).
I have provided reasonable evidence here, that Mary Gano was indeed the wife of John Denman III. Now we need to see real evidence that John Denman III had a sister 26 years younger, born in Flushing, who married a Jeremiah Gannung of Flushing, NY. If it doesn't exist, then Martha must be moved somewhere else, wherever she belongs. If she was a Denman (and I've seen zero evidence of it, so far), then she must have been a niece of John III.
NOTE: John III and Mary Gano has a *daughter* (not sister) Martha, but she married JOHN CORY, according to Ms. Harris's Denman Family History. (Also on Findagrave, someone gave Martha Denman Cory's maiden name as "Parkhurst" with no documentation -- which is incorrect.)
https://www.findagrave.com/memorial/19163988/martha-cory
This is the link to Martha Denman Cory's tombstone, with the same date of death as was reported in "Denman Family History" in 1913. She is also buried in the same cemetery with the Denman family of colonial New Jersey. The Corys and Denmans were involved in the church, so I'm sure there are records or other evidence of this couple's marriage.
Anyway, I've been aware for many years about this and several other serious issues with the known (i.e. documented) lineages of my family tree. But I was obliged to wait until I had more time and inclination to set about the task of correcting them. Honestly, I would have been very happy to see a better genealogist than me take care of it before now, but unfortunately for whatever reasons that never happened and instead certain details just seem to have gotten progressively more and more inaccurate.
There is no need for speculation or guesswork on historical lineages that have already had a lot of published research and documentation done on them. The records are there, and we just need to make good use of them. Things have improved in recent years, since many of the old record books are now available to read online. Yay !!! That makes me so happy.