Hello Ms. White:
I saw your post from 2003 - I may be 11 years late, but I'm relatively new to genealogy so I hope my information is still useful to you
I have my maternal second great-grandmother as Mary Ann Tierney, b. 1829 in New Brunswick and who may have married an Alexander McLean sometime between 1851-1866 (inclusive). She also apparently had a sister, Margaret, but I don't have any information on Margaret - I'm having enough difficulty unraveling the McLean-Tierney-McGuire Gordian knot.
I hope this information is helpful. I also have quite a bit of other information on ancestors we may have in common and will be willing to share what information I have if you are also willing to share information.
I hope you have a great evening.