I searched the Irish Family History Foundation's database. It contains 11,500,000 surviving rcds for abt 60% of Irish counties. Rcds B4 1840 are sparse.
For Hugh Higgins B Roscommon, I found 2 B rcds: 1806 and 1808. There were NO M rcds in Co. Roscommon - ever. For Bridget Flanagan B Roscommon, I found 328 B rcds. For 1807 +/- 4 yrs, there are 11 B rcds. For marriages, there are 125 rcds. You can screen this database yourself using different date ranges.
For a Hugh and Bridget marriage 1848 +/- 4 yrs, I found 0 M rcds for Hugh and 32 for Bridget. Since there are no matching rcds for each, the rcds for Bridget are likely false positives.
For Patrick B 1852 +/- 2 yrs, I found 39 in all Ireland, with 5 in Roscommon, but none in Leitrim.
For Hugh Jr. B 1855 +/- 2 yrs, I found 6 B rcds in all Ireland, but just 1 in Leitrim and 1 in Roscommon.
For Thomas B 1860 +/- 2 yrs, I found 58 B rcds in all Ireland with 12 in Roscommon and 2 in Leitrim.
For Mary B 1861 +/- 2 yrs, I found 96 B rcds in all Ireland, with 13 in Roscommon and 6 in Leitrim.
For Edward B 1867 +/- 2 yrs, I found 10 B rcds in all Ireland, with 6 in Roscommon and 0 in Leitrim.
If I were to guess at a DOB for Bridget, I would use 1828 +/- 4 yrs as a starting point. For Hugh, I would use 1826 +/- 4 yrs.
Google the Foundation's name to lead you to this database. Pls post your search results to my Genforum msg.