- per the certified record of death from the Riverhead County Clerk's office, John's father was Christopher Hempstead.
- per his widow Mary's application, the date of their marriage was 5 July 1856 at Riverhead, NY, by Rev. M. Lockwood, "there being no legal barrier to the marriage". There was also a spot for the name of any prior spouse of John's or claimant to his pension, which was left blank. However, in 1857 he was in jail in Suffolk County on charges of bigamy.
Pho(e)be [named probably after his sister Phoebe Morrell] was born in 1857. The date of John's marriage to Mary Walton  indicates to me that Charles was born by his first wife, Phoebe by his second. In 1857, evidently, his first wife was still living and they were still legally married, thus the bigamy charges. By 1865, when John resided Riverhead with his wife Mary, his first 2 children Charles & Phoebe lived with them. Was his first wife then deceased? Was there some other reason the children [or child, if only Charles belonged to the first wife] would not be living with their mother?
- Mary Walton perhaps had a brother Charles, who was married to a woman named Mary, and they had a daughter Phebe almost the same age as Pho(e)be Hempstead would be.
- Mary had a brother Charles, and she and her daughter Phebe lived with him [along with younger brother Silas.] She used the Walton surname because of her husband's bigamy charges.
- This is Mary Walton Hempstead, with John's son Charles who should be age 4 or 5, and their daughter Pho(e)be who was actually age 3. Also living with them was Mary's younger brother Silas Walton [who did appear in other censuses]. At present, I think this hypothesis is the correct one.