very new to this search and process - and your post is from so long ago, I'm assuming you've found the info your looking for. If not - here is what I have.
John Halstead, Orange County, NY born 1861- 1862, wife Minnie, children: Stanley Halstead 1894, married Mabel Van Inwegan 1898; Leona Halstead 1903, married John Andrew Kopp 1878, I think they had a son named Lee; Charles William Halstead 1891 married Blanche Budd 1900, they had 4 children, Ethel, Arthur, Edith and Alice.
If that is the John Halstead that you are looking for,
I think his father was William Halstead, and that he had a brother William and a brother James.
If you've signed up for membership on ancestry, try checking the Kopp or Van Inwegan, or Hogan family tree, they most likely have the info you're looking for.
the 1880 census records for John Halstead family, list the name as Aldstead or Adlstead, someone corrected it a while ago. Also (you probably already know this - but) you might try using Sullivan county or Mamakating instead of Orange county.
If you now have (2012) info beyond William, would really like to here from you.