Hi
There is a site here listing the family though no further back then you have except if you click furthre back on surnames it suggests some of these families were of Scotland or Conneticut...might be worth just a look.

http://www.trenholm.org/allensNB/WC14/WC14_052.htm

Might be worth looking in USA. I had same issue whether or not family was loyalist or not and some were found in Quebec, others NFLD but some had come from NewEngland states to Quebec or vica versa...it's tough searching and NFLD surprised the heck out of me.

I did note on NFLD Grandbanks site one McGlashing Elwood of Amherst Cape Tormentine marrying in NFLd to Francis Sainbury residing in Amherst born NFLD May 28 1888 he is 37 parents Father Tremain mother Miriam so he is born aobut 1851.