Mary, you can reach me at address removed by moderator
I wonder if Rose came over into the US with her (presumed) brother Pat (assuming you don't know Pat's parents). Rose is the one who married François Levesque in Sainte-Catherine-de-la-Jacques-Cartier in 1834. There is an Irish community there at the time. Still many Irish headstone in the cemetery, but no McDunns.
In earlier threads, she is said to be form co. Sligo, but I was never able to trace that in primary records, it was just in hand-me-down trees. Her marriage records states clearly she was from Westmeath. But with no town or parish to hang you hat on...