Corwin's own mother-in-law, Margaret Sheaf Thacher (née Webb; born 1625, Boston, to Henry and Dorabell (née Smith) Webb — died February 23, 1694, Boston), was accused of witchcraft by her servant, Mercy Short.[4] Thacher held extensive holdings in Boston, including her home and acreage which was next to Governor William Phips' house. Several years after her first husband's death, she married the Reverend Thomas Thacher. From 1669 to his death in 1678, Thacher served as the founding minister of the Old South Church.