Hi, I have found some info on Mary's family -- perhaps you already have this:
Mary Sellars b. 1798 Nova Scotia d. 1874 daughter of Donald and Margaret Sellars
Dennis Doyle d. 1868 age 87 born in Ireland to Patrick & Anastasia Doyle
- child William Doyle 1839-1875 never married
- child John Francis Doyle b. 1845
- child Isabel Doyle b. 1835 -- son Alexander Doyle (father Alex Chisholm according to Alexander's death record) 1865-1939 -- Isabel Doyle married at the age of 46 to John Boles.
You can verify info at www.novascotiagenealogy.com