By a great stroke of luck, one baptism for my Danson family was actually indexed as Danson in the Drouin collection on Ancestry.com. All the rest, or nearly all, were indexed as Dawson! It is entirely possible that other records for this family in the same collection are indexed under some other name that I haven't thought of yet.
The story so far:
John Danson, captain of the brig Frances, arrived in the port of Quebec on 02 jun 1818. He was from Workington, Cumberland, England, born about 1796. On 06 jun (4 days later) he was married (Holy Trinity, Anglican) to Catherine, daughter of the late Michael Power of Waterford, Ireland. She was born about 1797. Also present at the wedding were Catherine's mother Eliza Power, her brother William Power, and her sister Mary Jane Bradley.
What may be their first child was baptised in Workington, England in 1819. The next trace is a series of children baptised at Notre-Dame de Québec 1827-1834. They are indexed as Dawson, but the text says Danson and the names of both parents are given.
I have not been able to learn anything about William Power or his sister. He is not the William Power who was a schoolteacher, that one was a son of Roger Power of Waterford.
There are a few mentions of Danson (or Dawson) on the Ships List site, and I can follow some of the movements of John Danson through Lloyd's Register, which has allowed me to trace the movements of his ship, the Frances, 1810-1822. (It first belonged to William Danson, possibly John's father).
Since the Drouin index is so horribly inaccurate -- all sorts of goofy errors were found just looking for Danson and Power -- I'm looking for suggestions for other sources that might be checked.