Interesting...the information that you have is in keeping with the oral history in our family. We've heard that Arabella (Mi'kmaq) may have been born in Nova Scotia and relocated to Newfoundland somewhere along the way. (The surnames Brett/Britt and Rolf/Rolfe fit with the observation that many Mi'kmaq surnames are French.)
Like you, I've found documents verifying that Arabella Brett/Britt Rolfe/Rolf and Zacharias William Webber were in Newfoundland as of 1895, but not much before or after that date.
I've made a few local connections in the Corner Brook area and need to really start to look into things on this end (public library microfiche, church records, local groups that can assist with genealogical studies).
I'll stay in touch! Thanks for responding so soon!