There is a choice of two Kate, either ten or twenty years younger.
Mary Bryant died St. Hilary buried 3/7/1807 aged 62 so born C 1745; her age at children's births:- 22 25 28 30 35
or
Mary Briant died St. Hilary buried 24/8/1825 aged 91 so born 1734 lived at the Downs.
her age at children's births: 33 36 39 41 46

but then the children could be shared between them both!!