I research the Irish Family History Foundation's database. It contains 12,700,000 surviving rcds for abt 70% of Irish counties. Rcds are increasingly sparse B4 1840, rare B4 1800.
There are 506 B rcds for the Mattimoe surname + variants in Ireland, with 340 in Co. Roscommon alone, but none in Frenchpark. The earliest date from 1793 - just before the Revolution. This is far more than would be expected from a single refugee - there must have been others.
For Pat(rick) Conlin M 1809-1835, Co. Sligo, or Roscommon, I found 11 rcds within a relevant range: 1821R, 1823R, 2-1824RR, 1825R, 1828R, 2-1831RR, 1833R, 1835R, 2-1836RR, 1837R, 1838S, 2-1839RR, 2-1841RS, 2-1842RR, 3-1843R, 2-1845RS, 2-1846RS, and 1848S.
For Bri(dget) Mattimoe M ditto with a father's forename beginning with J, I found 4 rcds: 1833 Sligo, 1837 Sligo, 1839 Roscommon, and 1848 Roscommon. Only the 1839 Roscommon rcds have commonality. However, a screen at the parish level shows a NO match. The M event didn't survive, or occurred in an area not in the database - such as England.
Suggest you consult Burke's Peerage for the Marquis' lineage and issue.
Google the Foundation's name to lead you to this database. Register, opt to be notified as rcds are added and browse. Pls post your search results to my genforum msg.