Joseph Brown Jr. was born 1757 (his sister Elizabeth is confirmed date of birth 8 Jul 1757 - twins?? ). His headstone states "age 42", used to calculate his date of birth.
Research needed into children of Joseph and Miriam Davis. Their children include:
Upon Joseph's death Miriam m. Jonathan Hallock and had additional children by him.
Luther Brown is named the oldest son of Meriam Davis Brown in the "Ellen Brown" letter on Joseph Davis' profile page Davis-51670. There are only a few possible candidates:
The 1810 Census at Broookhaven (as well as the 1820, 1830 and 1840) list a Luther Brown, of the right age. In his immediate vicinity are many Davis (16) Hallock (5), and Brown (2) families. 
Deacon Luther Brown (1789-1863) can be eliminated, as he is documented as the son of Absolom Brown and Mary Elizabeth Mapes.
There is a Luther Brown in Orleans County, NY (1795-1883) but he appears to be the son of Luther Brown (1777-1862) also of Orleans County.
There is a Luther Brown who died in Castile, Wyoming County, NY FaG #5634699 aged 86?
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