The R1b1 Haplogroup you have listed for Zadock Briggs is completely wrong. My husband is a straight-line descendant of Zadock Briggs and both he and our son belong to the Haplogroup |1a. If you go to the FTDNA Briggs YDNA Project, my husband is Hap'group |1a-Family C, #20964. My son just took the YDNA-111 test and his numbers will post in a few months. Also, there is no proof whatsoever that William Briggs of RI is his father, or that Harriet Seymour was his wife.
Louise Briggs