In agreement with the responses from Mahlon Ericson, and to add a bit more, Jacob Beckwith was the brother of Manasseh Beckwith, and the guardian of his children after Manasseh's death. Jacob and Manasseh were the sons of Elisha Beckwith and Grace Leach, both of Connecticut. Both of these sons lived for some time in Louisville, Kentucky, but I think that they both still at least had holdings in New London, CT.
Manasseh was married to Jane Lawless (Filson Club, Early Jefferson Co, Ky Mgs Vol 1781-July 1826,(1980, pg145; book pg #120).), and their children were: 1. Mary Ann (who married 1. James Maxwell; and 2. John Copp), a. Caroline Beckwith Maxwell (m. Eben Richards had lots of kids) b. Grace Maxwell c. Henry/Harry Maxwell d. Irene Copp (never married, was living in Sacred Heart Home in Louisville in 1920) e. William Harmony Copp (who had a son named Joseph). 2. Caroline (who married ? Wales) 3. Charles.
Jacob mentions the following nieces and nephews in his will: Emily Darrow, Isaac N. Maynard, Maria Towne, Jacob B. Maynard, Elisha P. Rogers, Francis D. Rogers, Angenard Loomis, Nicholas Beckwith, and John Cavarly.
It appears that Jacob himself never married. I'd like to know which of his siblings the above children belonged to, although the two Maynards, are surely those of his sister, Sarah D. (Beckwith) Maynard.
I have not found data to indicate that Jacob had a brother named Ezra, but if you have, I'd be happy to know of it.