May i suggest a correction: after looking in other sites
John D.Horton m. Mary Marrington March 21, 1796 in Burton, Sudbury Co. (rootsweb - Horton Archives - post) Mary Marrington Horton is the one remarried to Solomon Whitlock not Mary Emma, her daughter. Solomon Whitlock would have died around 1830. The 1851 N.B. Census shows Whitlock Mary F Mother 85 United States 1766 Widowed Horton Abigail F. F Daughter 35 Native Johnson Ebenezer H. M Grandson 13 Native
Angus Johnson is mentioned in N.B. as a teacher.Is it possible that he moved to Ontario to be teacher or maybe headmaster? Did not find anything on Mary Emma his wife.