My GG grandmother Isabella married a John Cree ca 1847. I do not know her maiden name but I found that an Isabella Cammock married a John Crea in 1847. Her first child was a daughter Christina b 1848. Her second child was Elizabeth Jane 1852, my G grandmother Mary was b 1854. Her name was written Mary Hanna!!! I thought that it was a misprint for Hannah but now perhaps it is further evidence for Isabella to be a Cmmock. Her father named as David on the marriage certificate. She was born about 1820. Does this tie in with any of the family history that you have.