Hi Churchmouse,
There are a few Connochies buried in the Old Parish Churchyard in Larbert. The family in the attached photo would roughly match the dates for your Alexander and Margaret.
The following list are all the Connochies (including the ones from the photo) who have existing/legible stones in the same Churchyard. Some of the older stones are quite difficult to read so if I've got some of the dates wrong - sorry! I've got the full inscriptions and photos for each of them so if you think any others are likely candides, ket me know and I'll send you through the details (and photos)
CONNOCHIE, Agnes, died 1929, aged ? m
CONNOCHIE, Alexander, died 03.12.1868,aged 63
CONNOCHIE, Alexander, died 07.02.1932,aged 85
CONNOCHIE, Alexander
CONNOCHIE, Ann died 16.04.1869, aged 4
CONNOCHIE, Ann (Inglis?), died 31.03.1873, aged 31
CONNOCHIE, Archibald, died 31.03.1875 , aged 10m
CONNOCHIE, David, aged 3
CONNOCHIE, James
CONNOCHIE, Janet (nee Morrison)
CONNOCHIE, Janet (nee Scott)
CONNOCHIE, Jessie , died 24.05.1869, aged 6m
CONNOCHIE, Maggie
CONNOCHIE, Margaret, died 19.06.1866, aged 6
CONNOCHIE, Margaret, died 28.06.1896 , aged 81
CONNOCHIE, Mary A., died 10.03.1873, aged 17m
CONNOCHIE, William, died 05.04.1869, aged 2
CONNOCHIE, William
Anne