Looking at this again I think that Henry is Peter's grandfather.
There appear to be two James Dumas of Cloghereen alive at the same time: Dumas-585 and Dumas-907. The reason there are separate profiles is that Dumas-585 was supposedly 40 when he died according to transcript of his gravestone. I think he was about 10 years older which is why he inherited and not his brother Peter who must have been younger.
Sue had Henry as the son of Jacques/ James Dumas of Dublin. That's a reasonable deduction. However given Jacques/ James' son Peter was a minor in 1707 the birth date of 1680 shown on his profile is wrong.
As for Henry we don't know when he was born. The Henry born in 1699 was the son of a Peter.
Moving back to Jacques/ James, I suspect he was not from Poitou but from Alès in Languedoc. In 1709 a Nicholas Dumas died and his parents were given as the late Jacques Dumas and Susanne Lagarde.
