1/ If you look on www.tribalpages.com/tribes/atherton182 you will find a biography of Humphrey Atherton's early life in England which details his baptism entry, his parents names,his sisters and his grandparents.
2/ The Massachusetts Town, Probate & Vital Records lists the beneficiaries of Mary Atherton's will dated 21 February 1671. However, I do not have a copy of her actual will.
3/ The New England Historical & Genealogical Society published the will of Richard Mather dated 16 February 1661 and the codicil dated 21 July 1664. This names son Timothy and his wife Elizabeth. I know nothing about Catherine!
I live just a few miles away from where Humphrey was born.