Jonathan Farr III was styled the third to avoid confusion with other Jonathan's on the tax records. It in no way suggest lineage!
From Vanessa Herring:
Jonathan 3rd's last land transaction in Chesterfield was to sell 50 acres of Lot 11 in the 13th Range to Joseph Nurse of Dummerston, VT, on 8 Mar 1791. On the same day, Joseph Nurse sold Jonathan Farr 3rd of Chesterfield NH land in Dummerston, all of Lot 118 - 100 acres.
Jonathan Farr of Dummerston later sells 40 acres of Lot 118 to Peter Lamb of Dummerston, on 11 Oct 1794.
Only 2 months later (third Tuesday Dec 1794), Hannah Farr applied for her letters of administration "upon the estate of Jonathan Farr her late husband, late of Dummerston, deceased." Bond was provided by Thomas Farr (probably her son), and warrant to appraise was given. The inventory was completed 2 Jan 1795, mentioning a home farm and wild land.
From Vanessa Herring:
I've been doing an analysis of the land records for the 4 Jonathan Farrs of Chesterfield, to see if I can approximate the death year of Jonathan 1st. Here's what I've found:
First, we know that Jonathan Farr first was alive at the 1790 census, as were 2nd, 3rd, and 4th.
Jonathan 1st moved from Lot 5 11th Range, likely to be close to his sons in his old age. He purchased from Samuel Davis part of Lots 13 and 14 in the 14th Range on 5 Apr 1781. (He sold his Lot 5 11th Range land to Jonas Davis in 1785.)
Jonathan 2nd died about 25 Feb 1791.
Jonathan 3rd moved to Dummerston VT a little after his purchase of land there on 8 Mar 1791.
In administering Jonathan 2nd's estate in 1792, Jonathan 4th calls himself Jonathan 3rd, now 2nd in court papers. (The judge seems to ignore this, and always calls him Jonathan 3rd.) This would seem to indicate that the original Jonathan 3rd is no longer counted, since he has removed to Dummerston VT.
Likewise, Jonathan 4th does not take into account Jonathan 3rd, who is still living, but located in Dummerston VT by 1792. Selling estate land on 5 Dec 1793, he calls himself "Jonathan Farr 2nd, administrator of Jonathan Farr 2nd".
This would seem to indicate that Jonathan 1st is still living in 1793.
Jonathan 4th last called himself Jonathan 2nd in a deed on 8 Jan 1794. He first calls himself only Jonathan on a deed of 24 Apr 1794. It would appear that Jonathan 1st probably died during this time period.
By 1802, Jonathan 4th calls himself Esqr in his land transactions, and after his death in 1807 is referred to as Major Jonathan Farr by the administrator of his estate, John Kneeland.
Land transactions by John Kneeland reveal that Jonathan 4th's wife's name was Mary.