I'm in the process of transcribing the records of the RC parish where Francis and Margaret were born, married, and likely died. I have completed the first 50 years of marriages and 40 years of baptisms so far. They are linked to this index page:
http://ngb.chebucto.org/Parish/1ferr-parish-idx.shtmlIt appears that the ancestors of the Dillons in this area were:
Dillon Stephen Mulerackin, Wexford & Keenan Mary Toad's Cove (now Tors Cove, Newfoundland m. @ St. John's - Oct. 16, 1825 Witnesses: Michael Hearn & Catherine Driscoll [likely Mulrankin, Wexford]
The Blacklers were an English family, likely from Devonshire, but the records for their earliest ancestors have not been found. They settled at Mobile, where Stephen and Mary Keenan also settled after their marriage.
The Newfoundland settlement area for these families was Ferryland District (not St. John's West) and the RC parish was St. John's (pre 1831) and Bay Bulls/Witless Bay (post 1831). The District pages also have many other documents, such as directories, voter's lists, some death records, etc.
I hope this helps you get started.