Hello Cousin Joan:
Yes, William 1771 and 1773 were first cousins.
My William GARRETT 1773 md Catharine CANNELL, is descended from William GARRETT and Isabel McBooy (McBoyd); who is descended from William GARRETT and Jony CORJEAG(E); from Thomas GARRETT +/- 1658 but his wife's name is unknown.
I believe your William GARRETT 1771 md Isabel Cannell is descended from Robert GARRETT md Esther COWLEY; descended from William GARRETT and Jony CORJEAG(E); from Thomas GARRETT +/- 1658 but his wife's name is unknown.
Please contact me directly at msdaisy@island.net