Hi,
I have a copy of "East Preston Street Cemetery M.I.s" published by the Scottish Genealogy Society (2008). Unfortunately there are no memorials in the book for Susan Elder or James Brunton.
However there is an A. Brunton on the war memorial, and the following other stones:
1) Rev. Robert Elder, DD, West Free Church Rothesay b. Inverary 28/7/1808, d. edinburgh 30/3/1892, wife Margt Robson b. Oban 28/12/1807, d. Edinburgh 14/1/1901, dfaughter Julia b. Edin 24/9/1844, d. Edin 19/3/1846, daughter Margaret matilda b. Edin 1/4/1843, d. Edin 6/3/1924, Franmces Robson wife of Rev Alex Philip, Portobello, d. 17/10/1851.
2) Alexander Elder, d. 5/3/1842 aged 2(2) years 6 months, 2 son of William Elder, Bookbinder.
3) Walter Elder d. 27/9/1938, wife Jane Crichton d. 22/3/1950, son John d. 6/1/1901, Walter d. 20/4/1906.
Hope these might be of some use. They may or may not be related to Susan?
Contact Mortonhall Cremetorium to see the lair books.
Best wishes,
Craig