My Somerset Thatcher Family

I believe myself to be a direct descendant of John THATCHER/Mary CARY, married in Aller, Somerset, UK, on 2 Feb 1656, their daughter Joan, who married John SMALL of Othery on 22 May 1686. However, I can't make the connection to their daughter Joan, who married Arthur KEIRLE on 29 Nov 1732 in Othery. This couple made their home in Stoke St. Gregory. Their daughter Martha married George HUCKER in Othery on 23 Mar 1755. If anyone can help me make this connection, I would greatly appreciate it.