Hello, I think Mary Boyd who married John Kelso is daughter of John Boyd & Lillias Sterrat. Birth below. The daughter Mary of John Boyd & Mary Pringle died in 1820 and is buried in Stevenston. John Boyd's will mentions her children McKelvie.
Further to that if you can look up Landsborough Census for Stevenston will see Lillias Stirrat (widow) living next to John Kelso & Mary Boyd family.
BOYD
MARY
JOHN BOYD/LILLIAS STERRAT FR155 (FR155)
F
05/11/1788
615/
10 144
Stevenston
Kind regards
Sue Wyatt
