Regarding Mary Dering. I found her ancestry in a footnote on the Blayney family. The first husband of her grandmother, Margaret Moore, was Sir Henry, Baron Blayney. The footnote states that Margaret Moore married 2ndly to Charles Dering, Auditor of the Exchequer of Ireland, who was the son of Sir Edward Dering, 2nd Bt and Mary Harvey.

Margaret and Charles had a son, Henry Dering, who married Mary King, (widow of Chidley Coote, and daughter of Sir Robert King, 1st Bt Rockingham, and his wife Francis Gore).

Henry & Mary's daughter was Mary Dering who married Archdeacon Henry Cary
Mary Dering died in Trim on 1st July 1756 (reported in Gentleman's Magazine), presumable while travelling between Portarlington, where they lived, and Dublin.