Margaret's father - John Edgar having obtained on 23rd Dec., 1790, a decreet against John Rutherford, son and heir of the deceased John Rutherfurd of Hunthill, eldest son and heir of the deceased Henry Rutherfurd as lawfully charged to enter heir in special to deceased Sir John Nisbet of Dean, his second cousin, and to pay the principal sum of ; 10,000 sterling, as by bond. John Rutherfurd to John Edgar, dated i8th May, 1790.
"Scotland Births and Baptisms, 1564-1950," database, FamilySearch (https://familysearch.org/ark:/61903/1:1:XY3K-3QN : 2 January 2015), Margaret Edgar in entry for Agnes Lauder Rutherfurd, 19 Feb 1791; citing , reference 2:17RLMNR, index based upon data collected by the Genealogical Society of Utah, Salt Lake City; FHL microfilm 1,066,754.
"An account of the surname Edgar: and particularly of the family of Wedderlie in Berwickshire". - page 90