Thank you, Ruth. This is helpful.
The address recorded for the deaths of William and Euphemia is a croft called Loanhead of Corse which is still lived in today.
On the 1841 census there is a George Laing (b abt 1764), his wife Isobel (abt 1774), his son George (abt 1806, but abt 1802 on the 1851) and 3 minors are living at South Loanhead in Corse.
Scotlandspeople show George senior was born in Leochel Cushnie in 1764 to William Laing.
From someone else's research (not yet confirmed), children of William Laing & Mary Fraser of Leochel Cushnie were: William (1757), Peter (1761), George (1764), James (1767), Mary (1768), Francis (1769) and Francis (1771).
Scotlandspeople shows George Laing born 1802 in Leochel Cushnie to George Laing and Margaret Emslie who also have Peter in 1812.
There are children born to in Leochel Cushnie to George Laing and Isabel Emslie: John (1803), Martha (1805), Isabel (1807), Mary (1808), Elizabeth (1810), Martha (1814) and Charles (1816). There is also William Laing born to George Laing no mother shown in 1800.
Could Margaret and Isabel be the same person?
George Laing (1802) and his wife Elizabeth (maiden name may be Lawson) are living at South Loanhead in 1851 with infant daughter Elizabeth and stepson Alexander Copland.
On the 1861 there is a George Laing shown as born about 1812 with wife Elizabeth and daughter Elizabeth now 10 living at Loanhead with other children and a neice Isabel Laing born about 1825. It appears George dies at Loanhead in 1874.
The seems to be a connection with George Laing living at Loanhead and William Smith and Euphemia Laing dying there. Could Euphemia be the daughter of William (1757), Peter (1761), or possibly James (1767) Laing? I'll need to see what more I can find for them.